Outlook Therapeutics (OTLK) raises $55M to fund LYTENAVA U.S. launch

Rhea-AI Filing Summary

Outlook Therapeutics is a biopharmaceutical company commercializing LYTENAVA, the first FDA-, EU- and UK-approved ophthalmic bevacizumab for wet AMD. The company is offering 55,555,556 shares of common stock plus accompanying warrants to purchase 55,555,556 shares at a combined price of $0.99, for gross proceeds of about $55.0 million and estimated net proceeds of $51.1 million. Each warrant is immediately exercisable at $1.10 per share for five years. Underwriters have a 30‑day option for up to 8,333,333 additional shares and/or warrants.

Common shares outstanding are expected to rise to 242,672,554 (or 251,005,887 if the option is fully exercised), excluding warrant and option exercises and additional ATM issuances, implying meaningful dilution. Net proceeds, together with existing cash, are intended to fund the U.S. commercial launch of LYTENAVA and for working capital and general corporate purposes. Management estimates cash and cash equivalents of about $11.2 million as of June 30 2026 and discloses substantial doubt about the company’s ability to continue as a going concern without substantial additional capital. Outlook also carries a $19.8 million unsecured note to Atlas Sciences with quarterly redemption rights and a 7.5% exit fee, adding to financing risk.

Positive

• None.

Negative

• Management discloses substantial doubt about the ability to continue as a going concern even after this raise, highlighting ongoing dependence on new capital.
• Significant dilution from issuing 55,555,556 new shares (plus equal warrants) on a base of 187,116,998 shares and further overhang from options, warrants and ATM capacity.
• Outstanding unsecured promissory note of $19.8 million to Atlas with up to $3.0 million quarterly redemptions and a 7.5% exit fee increases financial pressure.
• Estimated cash of only $11.2 million as of June 30 2026 underscores tight liquidity ahead of a costly U.S. launch.

Key Figures

Shares offered: 55,555,556 shares of common stock Warrants offered: 55,555,556 purchase warrants Combined offering price: $0.99 per share and accompanying warrant +5 more

8 metrics

Shares offered 55,555,556 shares of common stock Primary offering size under the prospectus supplement

Warrants offered 55,555,556 purchase warrants One warrant issued with each offered share, exercisable for one share

Combined offering price $0.99 per share and accompanying warrant Public offering price for each share plus warrant unit

Gross proceeds $55,000,000.44 Aggregate gross proceeds from the base offering before expenses

Net proceeds $51.1 million Estimated net proceeds after underwriting discounts and expenses

Warrant exercise price $1.10 per share Initial exercise price of purchase warrants, exercisable immediately for five years

Estimated cash $11.2 million Estimated cash and cash equivalents as of June 30, 2026

Atlas note balance $19.8 million Principal, accrued interest and exit fees on March 2026 unsecured note as of March 31, 2026

Key Terms

going concern, At The Market Offering Agreement, Marketing Authorization, U.S. real property holding corporation, +2 more

6 terms

going concern financial

"There is substantial doubt about our ability to continue as a going concern"

Going concern is the accounting assumption that a company will keep operating and meeting its obligations for the foreseeable future. The phrase matters most when a company or its auditors disclose substantial doubt about it, a formal warning that the business may not have enough resources to continue without raising money, restructuring, or selling assets. That language in a filing or press release signals elevated financial risk.

At The Market Offering Agreement financial

"we entered into an At The Market Offering Agreement with H.C. Wainwright"

An at-the-market offering agreement is a contract that lets a company sell newly issued shares directly into the open market through a broker, at whatever price the stock is trading at that moment. For investors this matters because it can increase the number of shares available (which may dilute existing ownership) while providing a flexible, often faster way for the company to raise cash without fixing a price, similar to a vendor selling small batches at current market stalls rather than setting a single fixed price.

Marketing Authorization regulatory

"the European Commission granted a centralized Marketing Authorization for LYTENAVA"

An official government approval that allows a drug, vaccine, or medical device to be sold and promoted in a specific country or region. Think of it as a safety and effectiveness passport issued after regulators review the product’s tests and manufacturing; for investors, receiving this authorization typically unlocks sales, revenue potential, and lower regulatory risk, while delays or denials can substantially affect a company’s value and timeline.

U.S. real property holding corporation regulatory

"we are, or have been, at any time during the five-year period preceding such disposition a “U.S. real property holding corporation”"

passive foreign investment companies financial

"passive foreign investment companies and certain former U.S. citizens or long-term residents"

International Recognition Procedure regulatory

"the MHRA granted marketing authorization ... under the new International Recognition Procedure"

An international recognition procedure is the formal process by which one country or regulatory body accepts approvals, certifications, or decisions made by another, allowing a product, clinical result, or legal status to be used across borders without repeating the full review. For investors it matters because recognition can speed market entry, cut costs and lower regulatory risk—like a passport shortcut that lets a product reach more customers faster and with less uncertainty.

Offering Details

shelf

Offering

Offering Type shelf

Use of Proceeds Fund the commercial launch of LYTENAVA in the United States and for working capital and general corporate purposes.

FAQ

What is Outlook Therapeutics (OTLK) selling in this 424B5 offering?

Outlook is offering 55,555,556 shares of common stock plus warrants to buy 55,555,556 shares at a combined price of $0.99. Warrants are immediately exercisable at $1.10 per share and expire five years after issuance.

How much cash will Outlook Therapeutics (OTLK) receive from this offering?

Outlook estimates net proceeds of about $51.1 million, or $58.8 million if underwriters fully exercise their option. This excludes any additional cash from future warrant exercises at $1.10 per share.

How will Outlook Therapeutics (OTLK) use the proceeds from this deal?

The company plans to use net proceeds, with existing cash, to fund the U.S. commercial launch of LYTENAVA and for working capital and general corporate purposes. Management retains broad discretion over specific allocations.

What dilution will investors in Outlook Therapeutics (OTLK) face from this offering?

Shares outstanding are expected to increase to about 242.7 million (or 251.0 million if the option is exercised), excluding warrant and option exercises. The company estimates immediate dilution of roughly $0.75 per share to new investors at the $0.99 price.

What is the financial condition and going concern status of Outlook Therapeutics (OTLK)?

Management estimates cash and equivalents of about $11.2 million as of June 30 2026 and explicitly notes substantial doubt about continuing as a going concern without substantial additional capital, even with this financing.

What are the key terms of the Atlas Sciences note mentioned by Outlook Therapeutics (OTLK)?

As of March 31 2026, Outlook owed $19.8 million under a March 2026 unsecured note to Atlas, bearing interest at prime plus 3% (minimum 9.5%), maturing June 16 2027, with up to $3.0 million quarterly redemptions and a 7.5% exit fee on cash payments.

What is LYTENAVA and what approvals has Outlook Therapeutics (OTLK) obtained?

LYTENAVA is an ophthalmic formulation of bevacizumab for wet AMD. It is approved by the FDA, the European Commission, and the UK’s MHRA for adults with wet AMD, with planned U.S. commercial launch before December 31 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 08/14/2026 - 08:31 AM Accepted by SEC EDGAR 08/14/2026 - 08:30 AM Learn about SEC filing dates

TABLE OF CONTENTS

 As Filed Pursuant to Rule 424(b)(5)​

 Registration No. 333-278340​

PROSPECTUS SUPPLEMENT
(To Prospectus Dated April 5, 2024)

55,555,556 Shares of Common Stock
Warrants to Purchase 55,555,556 Shares of Common Stock

​

We are offering (i) 55,555,556 shares of our common stock, par value $0.01 per share and (ii) accompanying warrants, or the purchase warrants, to purchase up to an aggregate of 55,555,556 shares of our common stock (and the shares of common stock issuable from time to time upon exercise of each of the purchase warrants), pursuant to this prospectus supplement and the accompanying prospectus at a combined public offering price of  $0.99. Each share of common stock will be sold in combination with an accompanying purchase warrant to purchase one share of common stock issued for each share of common stock sold. The shares of our common stock and purchase warrants are immediately separable and will be issued separately. The purchase warrants will be exercisable immediately and will expire five years from the date of issuance. The purchase warrants will have an exercise price of  $1.10 per whole share of our common stock, subject to adjustment as described elsewhere in this prospectus supplement.

Our common stock is traded on The Nasdaq Capital Market under the symbol “OTLK.” On August 12, 2026, the last reported sale price of our common stock was $1.10 per share. There is no established public trading market for the purchase warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the purchase warrants on any securities exchange or recognized trading system.

We are a “smaller reporting company” under the federal securities laws and are subject to reduced public company reporting requirements. See the section entitled “Prospectus Supplement Summary— Implications of Being a Smaller Reporting Company.”

Investing in our securities involves a high degree of risk. Before making an investment decision, please read the information in “Risk Factors” beginning on page S-7 of this prospectus supplement and in our filings incorporated by reference into this prospectus supplement and the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

​

​

​

​

​

Per Share and Accompanying Purchase Warrant

​

​

Total

​

Combined public offering price

​

​

​

$

0.9900

​

​

​

​

$

55,000,000.44

​

​

Underwriting discounts and commissions(1)

​

​

​

$

0.0594

​

​

​

​

$

3,300,000.03

​

​

Proceeds to us, before expenses

​

​

​

$

0.9306

​

​

​

​

$

51,700,000.41

​

​

​

​

(1)

See the section titled “Underwriting” for additional information regarding compensation payable to the underwriters.

​

We have granted the underwriters an option for a period of 30 days to purchase up to an additional 8,333,333 shares of common stock at the public offering price allocable to the shares of common stock of $0.98 and/or purchase warrants to purchase up to 8,333,333 shares of common stock at the public offering price allocable to the warrants of $0.01, less the underwriting discounts and commissions.

The underwriters expect to deliver the securities against payment on or about August 14, 2026.

The shares of common stock will be settled via the Depository Trust Company. The purchase warrants will be delivered to purchasers in certificated form.

Joint Bookrunning Managers

Piper Sandler BTIG

Lead Manager

Brookline Capital Markets,

a division of Arcadia Securities, LLC

Prospectus supplement dated August 12, 2026.

TABLE OF CONTENTS​​

TABLE OF CONTENTS

​	​	​	Page				​
PROSPECTUS SUPPLEMENT							​
ABOUT THIS PROSPECTUS SUPPLEMENT	​	​	​	​	S-ii	​	​
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	​	​	​	​	S-iii	​	​
PROSPECTUS SUPPLEMENT SUMMARY	​	​	​	​	S-1	​	​
RISK FACTORS	​	​	​	​	S-7	​	​
USE OF PROCEEDS	​	​	​	​	S-12	​	​
DILUTION	​	​	​	​	S-13	​	​
Description of Securities We Are Offering	​	​	​	​	S-15	​	​
UNDERWRITING	​	​	​	​	S-24	​	​
LEGAL MATTERS	​	​	​	​	S-33	​	​
EXPERTS	​	​	​	​	S-33	​	​
WHERE YOU CAN FIND MORE INFORMATION	​	​	​	​	S-33	​	​
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	​	​	​	​	S-33	​	​

​	PROSPECTUS							​
​	ABOUT THIS PROSPECTUS	​	​	​	​	ii	​	​
​	PROSPECTUS SUMMARY	​	​	​	​	1	​	​
​	THE SECURITIES WE MAY OFFER	​	​	​	​	4	​	​
​	RISK FACTORS	​	​	​	​	7	​	​
​	SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	​	​	​	​	8	​	​
​	USE OF PROCEEDS	​	​	​	​	10	​	​
​	DESCRIPTION OF CAPITAL STOCK	​	​	​	​	11	​	​
​	DESCRIPTION OF DEBT SECURITIES	​	​	​	​	16	​	​
​	DESCRIPTION OF WARRANTS	​	​	​	​	22	​	​
​	LEGAL OWNERSHIP OF SECURITIES	​	​	​	​	24	​	​
​	PLAN OF DISTRIBUTION	​	​	​	​	27	​	​
​	LEGAL MATTERS	​	​	​	​	29	​	​
​	EXPERTS	​	​	​	​	29	​	​
​	WHERE YOU CAN FIND MORE INFORMATION	​	​	​	​	29	​	​
​	INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	​	​	​	​	30	​	​

S-i

TABLE OF CONTENTS​

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus relate to the offering of our securities. Before buying any of the securities that we are offering, we urge you to carefully read this prospectus supplement and the accompanying prospectus, together with the information incorporated by reference as described in the section titled “Incorporation of Certain Information by Reference” in this prospectus supplement and the accompanying prospectus and the information in any free writing prospectus that we may authorize for use in connection with this offering. These documents contain important information that you should consider when making your investment decision.

This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of our securities and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus dated April 5, 2024, including the documents incorporated by reference therein, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the Securities and Exchange Commission, or the SEC, before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

We have not, and the underwriters have not, authorized anyone to provide you with information different than or inconsistent with the information contained in or incorporated by reference into this prospectus supplement, the accompanying prospectus or in any free writing prospectus that we have authorized for use in connection with this offering. We and the underwriters do not take responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents, regardless of the time of delivery of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision regarding the securities we are offering. You should also read and consider the information in the documents to which we have referred you to in the section of this prospectus supplement entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”

Except as otherwise indicated herein or as the context otherwise requires, references in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein to “Outlook,” “the company,” “we,” “us,” “our” and similar references refer to Outlook Therapeutics, Inc., a Delaware corporation, and its subsidiaries on a consolidated basis.

This prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference include trademarks, trade names and service marks owned by us or other companies. The Outlook logo, Oncobiologics logo, LYTENAVA and other trademarks or service marks of Outlook Therapeutics, Inc. appearing in this prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference are the property of Outlook Therapeutics, Inc. This prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference also contains registered marks, trademarks and trade names of other companies. All other trademarks, registered marks and trade names appearing in this prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference are the property of their respective holders.

S-ii

TABLE OF CONTENTS​

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus, the documents we have filed with the SEC that are incorporated by reference and any free writing prospectus that we have authorized for use in connection with this offering contain “forward-looking statements” within the meaning of Section 27A of the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These statements relate to our future events, including our anticipated operations, research, development, manufacturing and commercialization activities, clinical trials, operating results and financial condition. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. Forward-looking statements may include, but are not limited to, statements about:

•

our ability to fund our working capital requirements, the sufficiency of our current cash resources and our need for additional funding;

​

•

our ability to maintain and establish collaborations or obtain additional funding;

​

•

our ability to successfully commercialize and generate revenues from the sale of LYTENAVA (bevacizumab-vikg, bevacizumab gamma), including our commercialization strategy, our ability to build a marketing and sales organization, and manufacturing capabilities for LYTENAVA;

​

•

the implementation of our business model and strategic plans for our business, LYTENAVA and any future product candidates;

​

•

our ability to compete in the markets we serve;

​

•

the rate and degree of market acceptance of our current and future product candidates;

​

•

our ability to successfully negotiate and enter into agreements with distribution, strategic and corporate partners;

​

•

our expectations regarding government and third-party payor coverage and reimbursement;

​

•

our expectations regarding the potential market size and the size of the patient populations for LYTENAVA and any other product candidates, if approved, for commercial use;

​

•

our reliance on contract manufacturing providers, distributors, device suppliers, testing laboratories, clinical research service providers, medical affairs, regulatory, and safety support providers, legal service providers, or other vendors or suppliers;

​

•

our ability to successfully source components of LYTENAVA and enter into supplier contracts;

​

•

developments or disputes concerning our intellectual property or other proprietary rights;

​

•

our ability to obtain and maintain regulatory approval for LYTENAVA in the US, EU, UK and other markets;

​

•

the initiation and success of our future research and development programs;

​

•

other factors that may impact our financial results; and

​

•

the anticipated net proceeds from this offering and the application of such proceeds.

​

In some cases, you can identify forward-looking statements by use of future dates or by terms such as: “anticipates,” “believes,” “continues,” “could,” “estimates,” “expects,” “intends,” “may,” “plans,” “seeks,” “should,” “will” and similar expressions intended to identify forward-looking statements. These statements reflect our current views with respect to future events, are based on assumptions and are subject to risks and uncertainties. Given these risks and uncertainties, you should not place undue reliance on these forward-looking statements. We discuss many of these risks in greater detail in “Risk Factors” contained on page S-7 of this prospectus supplement and in Exhibit 99.1 to our Current Report on Form 8-K, filed with the SEC on August 12, 2026, as updated by our subsequent filings, which are incorporated by reference into this prospectus supplement and the accompanying prospectus. Also, these forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Unless required by law, we undertake no obligation to update or

S-iii

TABLE OF CONTENTS

revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. You should carefully read this prospectus supplement, the accompanying prospectus and the documents incorporated herein and therein by reference as described in the section titled “Incorporation of Certain Information by Reference” in this prospectus supplement completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

S-iv

TABLE OF CONTENTS​

​

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information contained elsewhere in this prospectus supplement and the accompanying prospectus and in the documents we incorporate by reference. This summary does not contain all of the information you should consider before investing in our common stock. You should read this entire prospectus supplement and the accompanying prospectus carefully, especially the risks of investing in our securities discussed under “Risk Factors” beginning on page S-7 of this prospectus supplement and under the heading titled “Risk Factors” contained in Exhibit 99.1 to our Current Report on Form 8-K, filed with the SEC on August 12, 2026, as updated by our subsequent filings, which are incorporated by reference in this prospectus supplement and accompanying prospectus, along with our consolidated financial statements and notes to those consolidated financial statements and the other information incorporated by reference in this prospectus supplement and the accompanying prospectus, before making an investment decision.

Company Overview

We are a biopharmaceutical company that has developed LYTENAVA as the first and only ophthalmic formulation of bevacizumab approved by the US Food and Drug Administration, or FDA, the European Commission in the European Union, or EU, and the Medicines and Healthcare products Regulatory Agency, or MHRA, in the United Kingdom, or UK, for use in adults for the treatment of wet age-related macular degeneration, or wet AMD. Starting in June 2025, we launched directly into the initial markets of Germany and the UK. In 2026, we expanded into Austria and are planning for launches in other European countries either directly or with a licensing partner. In July 2026, we received FDA approval for LYTENAVA for the treatment of wet AMD in the United States, which results in 12 years of regulatory exclusivity in the United States. We are making preparations to commercially launch in the US prior to December 31, 2026.

Bevacizumab is a full-length, humanized anti-VEGF (Vascular Endothelial Growth Factor) recombinant monoclonal antibody, or mAb, that inhibits VEGF and associated angiogenic activity. Prior to the approval of LYTENAVA in the US, EU and UK, bevacizumab had only been approved for use in the treatment of various forms of cancer and had not been optimized for use in the treatment of retina diseases. Because there previously were no approved bevacizumab products for the treatment of retinal diseases in the United States and other major markets, we submitted standard biologic therapeutic applications and did not use the biosimilar drug regulatory pathway that would be required if bevacizumab were an approved drug for the targeted disease. Off-label repackaged bevacizumab is a frequently used first-line anti-VEGF treatment in the United States (approximately 2.2 million injections annually) and in Europe (approximately 2.8 million injections annually). We believe LYTENAVA has potential to mitigate risks associated with off-label use of unapproved bevacizumab. We believe there is significant opportunity in the United States, with an estimated $8.5 billion total anti-VEGF retina market, where 55% of physicians state off-label repackaged bevacizumab is the preferred first-line product. We similarly see significant opportunity in Europe with a total anti-VEGF retina market estimated to be approximately $3.6 billion, including approximately 1.52 million treated patients and approximately 8.3 million total anti-VEGF units. It is estimated that 34% of the total anti-VEGF market is off-label bevacizumab (new and maintenance therapy). We estimate the global market for anti-VEGF retina to be greater than $15.9 billion.

In May 2024, the European Commission granted a centralized Marketing Authorization for LYTENAVA for the treatment of adults with wet AMD in the EU. The decision applied automatically in all 27 EU Member States, and, within 30 days, also to Iceland, Norway and Liechtenstein. In July 2024, the MHRA granted marketing authorization for LYTENAVA for the treatment of wet AMD in the UK under the new International Recognition Procedure, or IRP, which allows the MHRA to rely on an authorization received for the same product from one of MHRA’s specified Reference Regulators, or RRs, when considering an application for marketing authorization in the UK. LYTENAVA is the first and only authorized ophthalmic formulation of bevacizumab for use in treating wet AMD in the United States, EU and UK.

Recent Developments

FDA Approval of LYTENAVA

On July 24, 2026, we announced that the FDA approved LYTENAVA for the treatment of wet AMD. The approval establishes LYTENAVA as the first and only FDA-approved ophthalmic formulation of

​

S-1

TABLE OF CONTENTS

​

bevacizumab for the treatment of wet AMD in the United States. We expect to make LYTENAVA available to eligible patients in the United States prior to December 31, 2026.

Financial Update

Based upon preliminary estimates and information available to us as of the date of this prospectus supplement, we estimate that as of June 30, 2026, we had cash and cash equivalents of approximately $11.2 million. This amount has not been audited, reviewed, or compiled by our independent registered public accounting firm. As a result, this amount is preliminary, is subject to normal quarterly closing processes and accounting review, and does not present all information necessary for an understanding of our financial condition as of June 30, 2026. Actual results for the three months ended June 30, 2026 will not be finalized until a later date and may differ materially from the above estimates. Our financial statements for the quarter ended June 30, 2026 will not be available until after this offering is completed, and consequently will not be available to you prior to investing in this offering.

May 2026 Offering

On May 29, 2026, we completed a registered direct offering to GMS Ventures and Investments, our largest stockholder, or GMS, priced at-the-market under Nasdaq rules for the purchase and sale of an aggregate of 8,539,709 shares of our common stock at an offering price of  $0.5855 per share of common stock, or the May Offering. In connection with the offering, on May 28, 2026, we entered into a warrant amendment with GMS pursuant to which we agreed to amend certain outstanding common stock warrants to purchase up to an aggregate of 15,488,570 shares of common stock previously issued to GMS in January 2025 and May 2025, with a weighted average exercise price of  $1.78 per share, effective upon the closing of the May Offering, such that the amended warrants have an exercise price per share of  $0.5855. The warrants otherwise remain unchanged. We received aggregate net proceeds from the May Offering of approximately $4.9 million.

April 2026 Offering

On April 23, 2026, we completed a registered direct offering priced at-the-market under Nasdaq rules for the purchase and sale of an aggregate of 16,129,033 shares of our common stock at an offering price of $0.31 per share of common stock. Additionally, in a concurrent private placement, or, together with the registered direct offering, the April Offering, we issued unregistered warrants to purchase up to an aggregate of 16,129,033 shares of common stock at an exercise price of  $0.31 per share. The unregistered warrants became exercisable on July 16, 2026 and will expire on July 21, 2031. We received aggregate net proceeds from the April Offering of approximately $4.2 million. Our potential additional gross proceeds from the unregistered warrants, if fully exercised on a cash basis, will be approximately $5.0 million. No assurance can be given that any of the warrants will be exercised for cash.

ATM Program

On May 13, 2026, we entered into an At The Market Offering Agreement with H.C. Wainwright & Co., LLC, or H.C. Wainwright, as agent, or the Sales Agreement, pursuant to which we may issue and sell shares of our common stock, from time to time, having an aggregate offering price of up to $100,000,000. As of July 31, 2026, we had sold 17,005,831 shares of common stock under the Sales Agreement for aggregate gross proceeds of  $14.6 million.

Risks Associated with this Offering

Our business is subject to a number of risks of which you should be aware before making an investment decision. These risks are discussed more fully in the “Risk Factors” section of this prospectus supplement immediately following this prospectus supplement summary and in Exhibit 99.1 to our Current Report on Form 8-K, filed with the SEC on August 12, 2026, as updated by our subsequent filings which are incorporated by reference in this prospectus supplement and accompanying prospectus. These risks include the following:

•

There is substantial doubt about our ability to continue as a going concern, which substantial doubt may not be alleviated with the net proceeds from this offering. We will need to raise substantial additional capital to fund the commercialization of LYTENAVA and support our operations until we are able to generate sufficient revenue from the sales of LYTENAVA. This

​

​

S-2

TABLE OF CONTENTS

​

additional funding may not be available on acceptable terms or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our commercialization and product development efforts or other operations;

•

Raising additional capital, including as a result of this offering, may cause dilution to our securityholders, restrict our operations or require us to relinquish rights to our technologies or product candidates;

​

•

The trading price of our securities is likely to be volatile, and purchasers of our securities could incur substantial losses;

​

•

If you purchase securities in this offering, you will suffer immediate dilution of your investment;

​

•

There is no established public trading market for the purchase warrants offered hereby, and we do not expect one to develop; and

​

•

We have broad discretion over the use of our cash and cash equivalents, including the net proceeds we receive in this offering, and despite our efforts may not use them in a manner that increases the value of your investment.

​

Our Intellectual Property

Our commercial success depends in part on our ability to avoid infringing the proprietary rights of third parties, our ability to obtain and maintain proprietary protection for our technologies where applicable and to prevent others from infringing our proprietary rights. We seek to protect our proprietary technologies by, among other methods, evaluating relevant patents, establishing defensive positions, monitoring EU oppositions and pending intellectual property rights, preparing litigation strategies in view of the US legislative framework and filing United States and international patent applications on technologies, inventions and improvements that are important to our business. As of March 31, 2026, we own three US patents, and twenty-two foreign patents, which relate to formulations developed for our legacy biosimilar program ONS-3010 and ONS-5010/ONS-1045, methods of antibody purification, methods for purifying antibodies to separate isoforms, methods of use, methods of reducing high molecular weight species, and modulating afucosylated species as well as efficiently determining the amino acid sequence of antibodies. Our Patent Cooperation Treaty, or PCT, Application No. PCT/US2017/016040, was filed in 2017. A US patent in this family is granted and expected to expire no earlier than 2037. Our PCT Application No. PCT/US2017/012349, was filed in 2017. Patents are granted in Australia and Japan and expected to expire no earlier than 2037. Our Application No. PCT/US2016/068847 was filed in 2016. Patents in this family are granted in Germany, France, United Kingdom, India, and Japan, and expected to expire no earlier than 2036. Our PCT Application No. PCT/US2016/014252 was filed in 2016. Patents in this family are granted in Germany, France, United Kingdom, and the US, and expected to expire no earlier than 2036. Our PCT Application No. PCT/US2017/016549 was filed in 2017. A patent in this family is granted in Japan, and expected to expire no earlier than 2037. We also rely on trade secrets, know-how and continuing technological innovation to develop and maintain our proprietary position.

The term of individual patents depends upon the legal term of the patents in countries in which they are obtained. In most countries, including the United States, the patent term is generally 20 years from the earliest date of filing a non-provisional patent application in the applicable country. In the United States, a patent’s term may, in certain cases, be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the United States Patent and Trademark Office in examining and granting a patent or may be shortened if a patent is terminally disclaimed over a commonly owned patent or a patent naming a common inventor and having an earlier expiration date.

Company Information

We initially incorporated in January 2010 in New Jersey as Oncobiologics, Inc., and in October 2015, we reincorporated in Delaware by merging with and into a Delaware corporation. In November 2018, we changed our name to Outlook Therapeutics, Inc. Our headquarters are located at 111 S. Wood Avenue, Unit #100, Iselin, New Jersey 08830, and our telephone number at that location is (609) 619-3990. Our website address is www.outlooktherapeutics.com. The information contained on, or that can be accessed through, our website is not part of, and is not incorporated by reference into this prospectus supplement or

​

S-3

TABLE OF CONTENTS

​

the accompanying prospectus, and you should not consider it part of this prospectus supplement or the accompanying prospectus. Our website address is included in this prospectus supplement as an inactive textual reference only.

Implications of Being a Smaller Reporting Company

We are a smaller reporting company as defined in the Exchange Act. We may take advantage of certain of the scaled disclosures available to smaller reporting companies and will be able to take advantage of these scaled disclosures for so long as (i) our voting and non-voting common stock held by non-affiliates is less than $250 million measured on the last business day of our second fiscal quarter or (ii) our annual revenue is less than $100 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700 million measured on the last business day of our second fiscal quarter. To the extent we take advantage of any reduced disclosure obligations, it may make the comparison of our financial statements with other public companies difficult or impossible.

​

S-4

TABLE OF CONTENTS

​

THE OFFERING

Common stock offered by us

55,555,556 shares.

Purchase warrants offered
by us

Purchase warrants to purchase up to 55,555,556 shares of our common stock. Each purchase warrant will have an initial exercise price per share of  $1.10, subject to certain adjustments, will become exercisable immediately, and will expire five years from the date of issuance. For more information, see the section titled “Description of Securities We Are Offering—Purchase Warrants” on page S-15 of this prospectus supplement. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon exercise of the purchase warrants.

Option to purchase additional securities

We have granted the underwriters an option, exercisable for a period of 30 days after the date of this prospectus supplement, to purchase up to an additional 8,333,333 shares of common stock and/or purchase warrants to purchase 8,333,333 shares of our common stock.

Common stock to be outstanding immediately after this offering

242,672,554 shares (or 251,005,887 shares if the underwriters exercise in full their option to purchase up to an additional 8,333,333 shares of our common stock, in each case, assuming none of the purchase warrants issued in this offering are exercised).

Use of proceeds

We estimate that the net proceeds from this offering, excluding the proceeds, if any, from the exercise of the purchase warrants offered hereby, will be approximately $51.1 million (or approximately $58.8 million if the underwriters exercise in full their option to purchase up to 8,333,333 additional shares of common stock) after deducting underwriting discounts and commissions and estimated offering expenses payable by us.

We intend to use the net proceeds from this offering, together with our cash and cash equivalents, to fund the commercial launch of LYTENAVA in the United States as well as for working capital and general corporate purposes. See “Use of Proceeds” for additional information.

Risk factors

Investing in our securities involves a high degree of risk. Before making an investment decision, please read the information contained in and incorporated by reference in this prospectus supplement and the accompanying prospectus under the section titled “Risk Factors” beginning on page S-7 of this prospectus supplement.

Nasdaq Capital Market
symbol

Our common stock is listed on The Nasdaq Capital Market under the symbol “OTLK.” There is no established public trading market for the purchase warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the purchase warrants on any securities exchange or recognized trading system.

The number of shares of our common stock to be outstanding after this offering is based on 187,116,998 shares of our common stock outstanding as of March 31, 2026, after giving pro forma effect to (i) the

​

S-5

TABLE OF CONTENTS

​

issuance and sale of 16,129,033 shares of common stock in the April Offering, (ii) the issuance and sale of 8,539,709 shares of common stock in the May Offering, (iii) the exercise of warrants to purchase 16,495,000 shares of common stock between April 1, 2026 and July 31, 2026, (iv) the issuance of 24,333,206 shares of common stock upon the conversion of approximately $9.8 million in principal and accrued interest under our prior convertible note between April 1, 2026 and July 31, 2026 and (v) the issuance and sale of 17,005,831 shares of common stock under our Sales Agreement between April 1, 2026 and July 31, 2026 for aggregate gross proceeds of approximately $14.6 million. This number excludes the following:

•

6,355,161 shares of common stock issuable upon exercise of outstanding stock options granted under our 2024 Equity Incentive Plan, or the 2024 Plan, as of March 31, 2026, with a weighted-average exercise price of  $6.70 per share;

​

•

1,134,419 shares of common stock issuable upon exercise of stock options granted between April 1, 2026 and July 31, 2026 under our 2024 Plan, with a weighted average exercise price of $1.42 per share;

​

•

1,528,065 shares of common stock reserved for future issuance under the 2024 Plan as of March 31, 2026;

​

•

47,407 shares of common stock reserved for future issuance under our 2016 Employee Stock Purchase Plan, or the ESPP, as of March 31, 2026, as well as any future automatic annual increases in the number of shares of common stock reserved for issuance under the ESPP;

​

•

57,591,978 shares of common stock issuable upon exercise of outstanding warrants as of March 31, 2026 (after giving effect to the warrants issued in the April Offering and the exercises discussed above) with a weighted-average exercise price of  $1.98 per share; and

​

•

up to $85.4 million of shares of our common stock remaining to be sold under the Sales Agreement as of August 1, 2026.

​

Unless otherwise indicated, all information in this prospectus supplement assumes:

•

no exercise of outstanding options or warrants to purchase our common stock;

​

•

no exercise by the underwriters of their option to purchase from us up to an additional 8,333,333 shares of common stock;

​

•

no issuance of shares available, or that may become available, for future issuance under our equity compensation plans; and

​

•

no exercise of the purchase warrants to be issued in this offering.

​

​

S-6

TABLE OF CONTENTS​

RISK FACTORS

Investing in our common stock involves a high degree of risk. Before you decide to invest in our securities, you should carefully consider the following risk factors and the risk factors in Exhibit 99.1 to our Current Report on Form 8-K, filed with the SEC on August 12, 2026, as updated by our subsequent filings, which are incorporated by reference into this prospectus supplement and accompanying prospectus in their entirety, together with all of the other information contained in this prospectus supplement and the accompanying prospectus or incorporated by reference into this prospectus supplement and the accompanying prospectus. The risks and uncertainties described in these documents are not the only ones we face. Other risks and uncertainties, including those that we do not currently consider material, may impair our business. If any of the risks discussed below or incorporated by reference actually occur, our business, financial condition, operating results or cash flows could be materially adversely affected. This could cause the value of our securities to decline, and you may lose all or part of your investment.

Risks Related to this Offering

There is substantial doubt about our ability to continue as a going concern, which substantial doubt may not be alleviated with the net proceeds of this offering. We will continue to need to raise substantial additional capital to fund the commercialization of LYTENAVA and support our operations until we are able to generate sufficient revenue from the sales of LYTENAVA. This additional funding may not be available on acceptable terms or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our commercialization and product development efforts or other operations.

Developing and commercializing pharmaceutical products are expensive, risky and lengthy processes. LYTENAVA has been approved for marketing for the treatment of wet AMD in adults in the US, EU and UK, however, we have not generated material revenue from sales of LYTENAVA. We expect to incur increased expenses in connection with our ongoing activities, particularly as we prepare to commercially launch in the US and continue with our commercial efforts in the EU and UK.

If our existing cash and cash equivalents, together with the net proceeds of this offering, are not adequate to fund our currently planned operations through at least the 12 months from the date of this prospectus supplement, there may be substantial doubt about our ability to continue as a going concern following the completion of this offering. We will require substantial additional capital to continue to operate as a going concern. Although we continue to pursue discussions with additional potential strategic partners for LYTENAVA outside of the US, there is no guarantee that we will be successful in reaching any such agreement, nor that such agreement, if successful, will cover the anticipated commercialization costs for LYTENAVA. Our operating plan may also change as a result of many factors currently unknown to us, and we may need to seek additional funds sooner than planned, through public or private equity or debt financings, third-party funding, marketing and distribution arrangements, as well as through other collaborations, strategic alliances and licensing arrangements, or a combination of these approaches. Even if we believe we have sufficient funds for our current or future operating plans, we may seek additional capital if market conditions are favorable or if we have specific strategic considerations.

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our product candidates. In addition, we cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. We may experience difficulties in accessing the capital markets due to external factors beyond our control, such as volatility in the equity markets for emerging biotechnology companies and general economic and market conditions both in the US and abroad. For example, our ability to raise additional capital may be adversely impacted by global economic conditions and disruptions to and volatility in the credit and financial markets in the US and worldwide, such as has been experienced recently due in part to, among other things, the impacts of inflation, ongoing overseas conflict, and disruptions in access to bank deposits and lending commitments due to bank failure. We cannot be certain that we will be able to obtain financing on terms acceptable to us, or at all. Our failure to obtain adequate and timely funding will adversely affect our business and our ability to launch and commercialize LYTENAVA and develop our technology and product candidates. Moreover, the terms of any financing may negatively impact the holdings or the rights of our stockholders, and the issuance of additional securities, whether equity or debt, by us or the possibility of such issuance may cause the market price of our securities to decline. The incurrence of indebtedness could result in increased fixed payment obligations, and we may be required

S-7

TABLE OF CONTENTS

to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. We may be required to relinquish rights to some of our technologies or product candidates or otherwise agree to terms unfavorable to us, in order to obtain necessary funding, any of which may harm our business, operating results and prospects. If we are unable to obtain funding on a timely basis, we may be required to significantly curtail, delay or discontinue the commercialization of LYTENAVA. We may also be unable to expand our operations or otherwise capitalize on our business opportunities, as desired, which could harm our business, financial condition and results of operations. Additionally, if we are unable to obtain the substantial additional funding needed to operate our business, our business and prospects would be materially and adversely affected, and we may be required to cease operations entirely, liquidate all or a portion of our assets, and/or seek protection under the US Bankruptcy Code, and our stockholders may lose all or part of their investment.

As of March 31, 2026, we had $19.8 million of principal, accrued interest and exit fees outstanding under an unsecured promissory note issued to Atlas Sciences LLC, or Atlas, in March 2026, or the March 2026 Note. The March 2026 Note bears interest at the prime rate, as published in The Wall Street Journal, plus 3%, subject to a minimum rate of 9.5%, and which matures on June 16, 2027. Beginning on September 16, 2026, Atlas has the right to redeem up to $3.0 million of the outstanding balance under the March 2026 Note per calendar quarter. All cash payments made by us under the March 2026 Note, including prepayments, redemptions, or repayment at maturity, are subject to a 7.5% exit fee.

Raising additional capital, including as a result of this offering, may cause dilution to our securityholders, restrict our operations or require us to relinquish rights to our technologies or product candidates.

Until such time, if ever, as we can generate sufficient product revenues, we expect to finance our cash needs through a combination of equity and debt financings, as well as selectively continuing to enter into collaborations, strategic alliances and licensing arrangements. We do not currently have any committed external source of funding. To the extent that we raise additional capital through the sale of equity, including in this offering or via our Sales Agreement, or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect your rights as a securityholder.

Atlas has the right to redeem up to $3.0 million of the outstanding balance under the March 2026 Note per calendar quarter. All cash payments made by us under the March 2026 Note, including prepayments, redemptions, or repayment at maturity, are subject to a 7.5% exit fee. The March 2026 Note is unsecured and contains customary representations and warranties, affirmative and negative covenants, and provisions governing trigger events, events of default, and remedies. Trigger events include, among other things, failure to make payments when due, insolvency or bankruptcy-related events, the occurrence of certain fundamental transactions without Atlas’ consent, covenant breaches, and material misrepresentations. Upon the occurrence of certain trigger events, Atlas has the right to increase the outstanding balance of the March 2026 Note, subject to contractual limitations, and if a trigger event is not cured within specified time periods, it may result in an event of default. Upon an event of default, Atlas has the right to accelerate the outstanding balance, apply default interest of up to 22% per annum, and pursue available remedies.

Additional debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends, and may be secured by all or a portion of our assets. If we secure funds for the commercialization of LYTENAVA or development of any future product candidate through entering into collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish additional valuable rights to our technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds when needed, we may be required to terminate commercialization efforts for LYTENAVA or future product development, grant rights to develop and market LYTENAVA or other product candidates that we would otherwise prefer to develop and market ourselves or cease operations altogether.

The trading price of our securities is likely to be volatile, and purchasers of our securities could incur substantial losses.

The market price of our securities has been and will likely continue to be volatile. The stock market in general and the market in which we operate have experienced extreme volatility that has often been

S-8

TABLE OF CONTENTS

unrelated to the operating performance of particular companies. As a result of this volatility, investors may not be able to sell their securities at a profit. The market price of our securities could be subject to wide fluctuations in response to a variety of factors, including but not limited to:

•

the level of LYTENAVA sales in the US, EU and UK;

​

•

the perception of limited market sizes or pricing for LYTENAVA or any of our other product candidates;

​

•

failure to successfully develop and commercialize LYTENAVA or any of our other product candidates;

​

•

any inability to obtain additional funding;

​

•

the success of competitive services, products or technologies;

​

•

adverse results or delays in preclinical or clinical trials;

​

•

any delay in filing an IND, BLA or other regulatory submission for our product candidates when planned, and any adverse development or perceived adverse development with respect to the applicable regulatory agency’s review of that IND, BLA or other regulatory submission;

​

•

post-marketing safety issues relating to our product candidates generally;

​

•

failure to maintain our existing strategic collaborations or enter into new collaborations;

​

•

failure by us or our licensors and strategic collaboration partners to prosecute, maintain or enforce our intellectual property rights;

​

•

changes in laws or regulations applicable to our products;

​

•

any inability to obtain adequate product supply for our product candidates or the inability to do so at acceptable prices;

​

•

adverse regulatory decisions;

​

•

introduction of new products, services or technologies by our competitors;

​

•

failure to meet or exceed financial projections we may provide to the public;

​

•

failure to meet or exceed the financial projections of the investment community;

​

•

the perception of the pharmaceutical industry by the public, legislatures, regulators and the investment community;

​

•

announcements of significant acquisitions, strategic partnerships, joint ventures or capital commitments by us, our strategic collaboration partners or our competitors;

​

•

disputes or other developments relating to proprietary rights, including patents, litigation matters and our ability to obtain patent protection for our technologies;

​

•

additions or departures of key scientific or management personnel;

​

•

significant lawsuits, including stockholder litigation and litigation filed by us or filed against us pertaining to patent infringement or other violations of intellectual property rights;

​

•

the outcomes of any citizens petitions filed by parties seeking to restrict or limit the approval of LYTENAVA in the US, EU or UK, or any of our product candidates that may be approved;

​

•

if securities or industry analysts do not publish research or reports about our business or if they issue an adverse or misleading opinion regarding our stock;

​

•

changes in the market valuations of similar companies;

​

•

general economic, industry or market conditions;

​

•

sales of our securities by us or our stockholders in the future;

​

•

trading volume of our securities;

​

S-9

TABLE OF CONTENTS

•

issuance of patents to third parties that could prevent our ability to commercialize our product candidates;

​

•

the loss of one or more employees constituting our leadership team;

​

•

changes in regulatory requirements that could make it more difficult for us to develop our product candidates; and

​

•

the other factors described in this “Risk Factors” section or the risks discussed in Exhibit 99.1 to our Current Report on Form 8-K, filed with the SEC on August 12, 2026, as updated by our subsequent filings, which are incorporated by reference into this prospectus supplement and accompanying prospectus.

​

We and two of our current and former officers have been named as defendants in a class action lawsuit filed in the US District Court for the District of New Jersey and certain of our current and former officers and directors were named as defendants in a shareholder derivative action filed in the District Court of the District of Delaware. Such lawsuits have often been instituted against companies, including us, whose securities have experienced periods of volatility in market price. The pending lawsuits and any lawsuits brought against us in the future could result in substantial costs, which would hurt our financial condition and results of operations and divert management’s attention and resources, which could preclude or delay commercialization efforts.

In addition, biopharmaceutical companies in particular have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of our securities, regardless of our actual operating performance.

If you purchase securities in this offering, you will suffer immediate dilution of your investment.

The combined public offering price per share and accompanying purchase warrant in this offering is higher than the net tangible book value per share of our common stock. Therefore, if you purchase securities in this offering, you will pay a combined offering price per share and accompanying purchase warrant that substantially exceeds our pro forma as adjusted net tangible book value per share after giving effect to this offering. To the extent outstanding options or warrants are exercised, you will incur further dilution. Our net tangible book deficit as of March 31, 2026 was approximately $29.0 million, or $0.28 per share. After giving effect to: the pro forma adjustments described in the section of this prospectus supplement titled “Dilution” and the sale of the shares of our common stock and accompanying purchase warrants in this offering at a combined price of  $0.99 per share and accompanying purchase warrant, and after deducting the underwriting discounts and commissions and estimated offering expenses payable by us (but excluding the shares of common stock to be issued and the proceeds received, if any, from exercises of the purchase warrants offered hereby), you will experience immediate dilution of  $0.75 per share, representing the difference between our pro forma as adjusted net tangible book value per share as of March 31, 2026 after giving effect to this offering (but without giving effect to the exercise of the purchase warrants offered hereby). If the holders of the purchase warrants exercise the warrants in full, our pro forma as adjusted net tangible book value per share after this offering would be $0.39, representing an immediate increase in pro forma as adjusted net tangible book value per share of  $0.35 to existing stockholders and immediate dilution in pro forma as adjusted net tangible book value per share of $0.60 to new investors purchasing securities in this offering. See the section of this prospectus supplement titled “Dilution” for a more detailed discussion of the dilution you will incur if you purchase securities in this offering.

We have broad discretion over the use of our cash and cash equivalents, including the net proceeds we receive in this offering, and despite our efforts may not use them in a manner that increases the value of your investment.

Our management has broad discretion to use our cash and cash equivalents, including the net proceeds we receive in this offering, to fund our operations and could spend these funds in ways that do not improve our results of operations or enhance the value of our common stock. The failure by our management to apply these funds effectively could result in financial losses that could have an adverse effect on our business, cause the price of our common stock to decline and delay the development of our product candidates.

S-10

TABLE OF CONTENTS

There is no public market for the purchase warrants being offered by us in this offering.

There is no established public trading market for the purchase warrants being sold in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the purchase warrants on any securities exchange or recognized trading system. Without an active market, the liquidity of the purchase warrants will be limited.

The purchase warrants are speculative in nature. You may not be able to recover your investment in the purchase warrants, and the purchase warrants may expire worthless.

The purchase warrants do not confer any rights of our common stock ownership on their holders, such as voting rights, but rather merely represent the right to acquire shares of our common stock at a fixed price for a limited period of time. Specifically, commencing on the date of issuance, holders of purchase warrants may exercise their right to acquire the underlying common stock and pay an exercise price per share equal to $1.10, subject to certain adjustments, and the purchase warrants will expire five years after the date of issuance. Moreover, following this offering, the market value of the purchase warrants, if any, is uncertain and there can be no assurance that the market value of the purchase warrants will equal or exceed their imputed offering price. In addition, there can be no assurance that the market price of our common stock will equal or exceed the exercise price of the purchase warrants for a sustained period of time or at all, and, consequently, it may not ever be profitable for holders of the purchase warrants to exercise the purchase warrants.

Holders of the purchase warrants will have no rights as common stockholders until they acquire our common stock.

Until you acquire shares of our common stock upon exercise of the purchase warrants, you will have no rights with respect to our common stock issuable upon exercise of the purchase warrants, including the right to receive dividend payments, vote or respond to tender offers. Upon exercise of your purchase warrants, you will be entitled to exercise the rights of a common stockholder only as to matters for which the record date occurs after the exercise date.

If we do not maintain a current and effective registration statement relating to the shares of our common stock issuable upon exercise of the purchase warrants, holders will only be able to exercise such purchase warrants on a “cashless basis.”

If we do not maintain a current and effective registration statement relating to the shares of our common stock issuable upon exercise of the purchase warrants at the time that holders wish to exercise such purchase warrants, they will only be able to exercise them on a “cashless basis” provided that an exemption from registration is available. As a result, the number of shares of our common stock that holders will receive upon exercise of the purchase warrants will be fewer than it would have been had such holder exercised such purchase warrants for cash, and holders may be limited in their ability to immediately sell shares upon exercise subject to volume or other securities law limitations. Further, if an exemption from registration is not available, holders would not be able to exercise on a cashless basis and would only be able to exercise their purchase warrants for cash if a current and effective registration statement relating to the shares of our common stock issuable upon exercise of the purchase warrants is available.

S-11

TABLE OF CONTENTS​

USE OF PROCEEDS

We estimate that the net proceeds to us from this offering, excluding the proceeds, if any, from the exercise of the purchase warrants offered hereby, will be approximately $51.1 million, or approximately $58.8 million if the underwriters exercise in full their option to purchase additional shares of common stock, in each case after deducting underwriting discounts and commissions and estimated offering expenses payable by us. If all of the purchase warrants sold in this offering were to be exercised in cash at an exercise price of  $1.10 per share, we would receive additional net proceeds of approximately $57.4 million, or approximately $66.1 million if the underwriters exercise in full their option to purchase additional purchase warrants and such warrants were exercised in cash. We cannot predict when or if the purchase warrants will be exercised, and it is possible that the purchase warrants may expire and never be exercised.

We intend to use the net proceeds from this offering, together with our cash and cash equivalents, to fund the commercial launch of LYTENAVA in the United States as well as for working capital and general corporate purposes. These expected uses represent our intentions based upon our current plans and business conditions, which could change in the future as our plans and business conditions evolve. The amounts and timing of these expenditures will depend on numerous factors, including the development of our current business initiatives. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses for the net proceeds from this offering. Our management has broad discretion to use our cash and cash equivalents, including the net proceeds we receive in this offering, to fund our operations and investors will be relying upon the judgment of our management regarding the application of these proceeds. The failure by our management to apply these funds effectively could harm our business and cause the price of our common stock to decline, perhaps significantly. The amounts and timing of our actual expenditures will depend on numerous factors, including factors described under “Risk Factors” in this prospectus supplement and the documents incorporated by reference herein and therein. Pending these uses, we expect to invest the net proceeds in short-term, interest bearing obligations, certificates of deposit or direct or guaranteed obligations of the United States. The goal with respect to the investment of these net proceeds is capital preservation and liquidity so that such funds are readily available to fund our operations.

Based on the planned use of proceeds described above, we believe that the net proceeds from this offering, together with our current cash and cash equivalents, will be sufficient to enable us to fund our operating expenses and capital expenditure requirements into the second quarter of 2027. We have based this estimate on assumptions that may prove to be incorrect, and we could use our available capital resources sooner than we currently expect.

S-12

TABLE OF CONTENTS​

DILUTION

If you invest in our common stock in this offering, your interest will be diluted immediately to the extent of the difference between the public offering price per share you pay for in this offering and the as adjusted net tangible book value per share of our common stock after this offering. Our net tangible book deficit as of March 31, 2026 was approximately $29.0 million, or $0.28 per share of common stock. Net tangible book value is total assets minus the sum of liabilities and intangible assets. Net tangible book value per share is net tangible book value divided by the total number of shares of our common stock outstanding as of March 31, 2026.

Our pro forma net tangible book value as of March 31, 2026 was approximately $8.2 million, or $0.04 per share of common stock. Pro forma net tangible book value reflects total tangible assets minus total liabilities, adjusted to give effect to (i) the issuance and sale of 16,129,033 shares of common stock in the April Offering resulting in approximately $4.2 million of net proceeds, (ii) the issuance and sale of 8,539,709 shares of common stock in the May Offering resulting in approximately $4.9 million in net proceeds, (iii) the exercise of warrants to purchase 16,495,000 shares of common stock resulting in approximately $4.1 million in net proceeds, (iv) the issuance of 24,333,206 shares of common stock upon the conversion of  $9.8 million in principal and accrued interest under our prior convertible note and (v) the issuance and sale of 17,005,831 shares of common stock under our Sales Agreement resulting in approximately $14.1 million of net proceeds, each occurring subsequent to March 31, 2026.

Dilution in net tangible book value per share represents the difference between the amount per share paid by purchasers of securities in this offering, and the pro forma as adjusted net tangible book value per share of our common stock immediately after completion of this offering.

After giving effect to the issuance and sale of 55,555,556 shares of our common stock and accompanying purchase warrants to purchase an additional 55,555,556 shares of our common stock in this offering at the combined public offering price of  $0.99 per share and accompanying warrant (excluding the shares of common stock to be issued and the proceeds received, if any, from exercises of the purchase warrants), and after deducting the underwriting discounts and commissions and estimated offering expenses payable by us, our pro forma as adjusted net tangible book value as of March 31, 2026 would have been approximately $59.3, or $0.24 per share. This represents an immediate increase in the net tangible book value of  $0.20 per share to existing stockholders and immediate dilution in net tangible book value of $0.75 per share to the investors purchasing securities in this offering.

The following table illustrates this dilution on a per share basis to the investors participating in this offering without giving effect to the option to purchase additional shares granted to the underwriters:

​

Combined public offering price per share and accompanying purchase warrant

​

​

​

​

​

​

​

​

​

$

0.99

​

​

​

Net tangible book deficit per share as of March 31, 2026

​

​

​

$

(0.28)

​

​

​

​

​

​

​

​

​

Increase per share attributable to the pro forma adjustments described above

​

​

​

​

0.32

​

​

​

​

​

​

​

​

​

Pro forma net tangible book value per share as of March 31, 2026

​

​

​

​

0.04

​

​

​

​

​

​

​

​

​

Increase per share as a result of this offering

​

​

​

​

0.20

​

​

​

​

​

​

​

​

​

Pro forma as adjusted net tangible book value per share after this offering

​

​

​

​

​

​

​

​

​

​

0.24

​

​

​

Dilution per share to investors participating in this offering

​

​

​

​

​

​

​

​

​

$

0.75

​

​

If the underwriters exercise their option to purchase 8,333,333 additional shares in full at the public offering price of  $0.99 per share, the pro forma as adjusted net tangible book value will increase to $0.27 per share, representing an immediate increase to existing stockholders of  $0.23 per share and an immediate dilution of  $0.72 per share to investors participating in this offering.

If the holders of the purchase warrants exercise the purchase warrants in full, our pro forma as adjusted net tangible book value per share after this offering would be $0.39, representing an immediate increase in pro forma as adjusted net tangible book value per share of  $0.35 to existing stockholders and immediate dilution in pro forma as adjusted net tangible book value per share of  $0.60 to new investors purchasing securities in this offering. We have not yet determined whether the purchase warrants will be classified and accounted for as liabilities or as equity.

S-13

TABLE OF CONTENTS

Unless indicated otherwise, the above discussion and table are based on 187,116,998 shares of our common stock outstanding as of March 31, 2026, after giving pro forma effect to the adjustments outlined above. This number excludes the shares of common stock issuable upon exercise of the purchase warrants offered hereby (except as otherwise indicated above), and also excludes the following:

•

6,355,161 shares of common stock issuable upon exercise of outstanding stock options granted under the 2024 Plan as of March 31, 2026, with a weighted-average exercise price of  $6.70 per share;

​

•

1,134,419 shares of common stock issuable upon exercise of stock options granted between April 1, 2026 and July 31, 2026 under our 2024 Plan, with a weighted average exercise price of $1.42 per share;

​

•

1,528,065 shares of common stock reserved for future issuance under the 2024 Plan as of March 31, 2026;

​

•

47,407 shares of common stock reserved for future issuance under the ESPP as of March 31, 2026, as well as any future automatic annual increases in the number of shares of common stock reserved for issuance under the ESPP;

​

•

57,591,978 shares of common stock issuable upon exercise of outstanding warrants as of March 31, 2026 (after giving effect to the warrants issued in the April Offering and the exercises discussed above) with a weighted-average exercise price of  $1.98 per share; and

​

•

up to $85.4 million of shares of our common stock remaining to be sold under the Sales Agreement as of August 1, 2026.

​

To the extent that options and warrants are exercised or settle, as applicable, or other shares are issued, the investors purchasing in this offering may experience further dilution. In addition, we will need to raise additional capital, and, to the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to the investors participating in this offering.

S-14

TABLE OF CONTENTS​

DESCRIPTION OF SECURITIES WE ARE OFFERING

We are offering 55,555,556 shares of our common stock and accompanying warrants to purchase an additional 55,555,556 shares of our common stock, or the purchase warrants. Each share of our common stock will be sold with a purchase warrant to purchase one share of our common stock. The shares of our common stock and the accompanying purchase warrants are immediately separable and will be issued separately. The shares of our common stock issuable from time to time upon exercise of the purchase warrants, if any, are also being offered pursuant to this prospectus supplement and the accompanying prospectus.

Common Stock

Our restated certificate of incorporation, as amended, authorizes us to issue 600,000,000 shares of our common stock, par value $0.01 per share, and 10,000,000 shares of preferred stock, par value $0.01 per share. Shares of our common stock are the only security of the Company registered pursuant to Section 12 of the Securities Exchange Act of 1934, as amended. Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The affirmative vote of holders of 662∕3% of the voting power of all of the then-outstanding shares of capital stock, voting as a single class, will be required to amend certain provisions of our certificate of incorporation, including provisions relating to amending our bylaws, the classified board, the size of our board, removal of directors, director liability, vacancies on our board, special meetings, stockholder notices, actions by written consent and exclusive jurisdiction.

For more information, see “Description of Capital Stock” in the accompanying prospectus and in the documents incorporated by reference into this prospectus supplement and the accompanying prospectus.

Our common stock is listed on The Nasdaq Capital Market under the symbol “OTLK.” The transfer agent and registrar for our common stock is Equiniti Trust Company, LLC.

Purchase Warrants

The material terms and provisions of the purchase warrants being issued in this offering are summarized below. The following description is subject to, and qualified in its entirety by, the form of purchase warrant which will be filed as an exhibit to a Current Report on Form 8-K to be filed by us with the SEC in connection with this offering. You should review the form of purchase warrant for a complete description of the terms and conditions applicable to the purchase warrants.

General.   Each purchaser of a share of our common stock will receive a purchase warrant to purchase one share of our common stock. The purchase warrants will be delivered to purchasers in certificated form.

Exercisability.   The purchase warrants will be exercisable on the issuance date and will expire five years from the date of issuance. The purchase warrants will be exercisable, at the option of each holder, in whole or in part by delivering to us or the warrant agent a duly executed exercise notice and by payment in full in immediately available funds for the number of shares of our common stock purchased upon such exercise. However, if a registration statement registering the issuance of the shares of our common stock underlying a purchase warrant held by a holder under the Securities Act is not effective or available for the issuance of such shares to such holder at the time of exercise, the holder may only exercise the purchase warrant through a “cashless exercise,” in which case the holder would receive upon such exercise the net number of shares of our common stock determined according to the formula set forth in the purchase warrant. Apart from the limited circumstance where such a registration statement is not then effective or available, the exercise price must be paid by the holder in cash in immediately available funds.

Exercise Limitations.   A holder (together with its affiliates and other attribution parties) may not exercise any portion of a purchase warrant to the extent that immediately prior to or after giving effect to such exercise the holder would own more than 4.99%, 9.99%, or 19.99%, as applicable, of our outstanding common stock immediately after exercise, which percentage may be changed at the holder’s election to a higher or lower percentage not in excess of 19.99% (if exceeding such percentage would result in a change of control under Nasdaq Listing Rule 5635(b) or any successor rule) upon 61 days’ notice to us, subject to the terms of the purchase warrants.

Exercise Price.   The initial per share exercise price of the purchase warrants is $1.10. The exercise price is subject to adjustment in the event of stock combinations, subdivisions or similar events affecting our common stock.

S-15

TABLE OF CONTENTS

Transferability.   Subject to compliance with any applicable securities laws, the purchase warrants are separately tradeable immediately after issuance at the option of the holders and may be transferred at the option of the holders.

No Listing.   There is no established public trading market for the purchase warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the purchase warrants on any securities exchange or recognized trading system. Without an active market, the liquidity of the purchase warrants will be limited.

Fundamental Transactions.   In the event of a fundamental transaction, as described in the purchase warrants and generally including any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding common stock, or any person or group becoming the beneficial owner of more than 50% of the voting power represented by our outstanding common stock, the holders of the purchase warrants will be entitled to receive upon exercise of the purchase warrants the kind and amount of securities, cash or other property that the holders would have received had they exercised the purchase warrants immediately prior to such fundamental transaction. Notwithstanding the foregoing, as more fully described in the purchase warrant, in the event of certain fundamental transactions, the holders of the purchase warrants will be entitled to receive consideration in an amount equal to the Black Scholes value of the purchase warrants.

Rights as a Stockholder.   Except for the right to participate in certain dividends and distributions and as otherwise provided in the purchase warrant or by virtue of a holder’s ownership of shares of our common stock, the holders of the purchase warrants do not have the rights or privileges of holders of our common stock, including any voting rights, until they exercise their purchase warrants.

S-16

TABLE OF CONTENTS

MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES

The following is a general discussion of certain material United States, or U.S., federal income tax consequences of the purchase, ownership and disposition of shares of our common stock issued pursuant to this offering, or the Shares, the purchase, exercise, disposition and lapse of warrants to purchase shares of our common stock pursuant to this offering, or the purchase warrants and the ownership and disposition of shares of our common stock issuable upon exercise of the purchase warrants, or the warrant shares. The Shares, the purchase warrants and the warrant shares are collectively referred to herein as our “securities.” All prospective holders of our securities should consult their tax advisors with respect to the U.S. federal, state, local and non-U.S. tax consequences of the purchase, ownership and disposition of our securities.

This discussion is not a complete analysis of all potential U.S. federal income tax consequences relating to the purchase, ownership and disposition of our securities. This discussion is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, which we refer to as the Code, existing U.S. Treasury Regulations promulgated thereunder, published administrative pronouncements and rulings of the U.S. Internal Revenue Service, which we refer to as the IRS, and judicial decisions, all as in effect as of the date of this prospectus supplement. These authorities are subject to change and to differing interpretation, possibly with retroactive effect. Any change or differing interpretation could alter the tax consequences to holders described in this discussion. There can be no assurance that a court or the IRS will not challenge one or more of the tax consequences described herein, and we have not obtained, nor do we intend to obtain, a ruling with respect to the U.S. federal income tax consequences to a holder of the purchase, ownership or disposition of our securities.

We assume in this discussion that a holder holds our securities as a “capital asset” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular holder in light of that holder’s individual circumstances, nor does it address any alternative minimum, Medicare contribution, estate or gift tax consequences, the special tax accounting rules under Section 451(b) of the Code or any aspects of U.S. state, local or non-U.S. taxes or any other U.S. federal tax laws. This discussion also does not address consequences relevant to holders subject to special tax rules, such as holders that own or have owned, or are deemed to own or have owned, more than 5% of our capital stock (except to the extent specifically set forth below), corporations that accumulate earnings to avoid U.S. federal income tax, tax-exempt organizations, governmental organizations, banks, financial institutions, investment funds, insurance companies, brokers, dealers or traders in securities, commodities or currencies, regulated investment companies or real estate investment trusts, persons that have a “functional currency” other than the U.S. dollar, tax-qualified retirement plans, “qualified foreign pension funds” as defined in Section 897(l)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds, holders who hold or receive our securities pursuant to the exercise of employee stock options or otherwise as compensation, holders holding our securities as part of a hedge, wash, straddle or other risk reduction strategy, conversion transaction or other integrated investment, holders deemed to sell our securities under the constructive sale provisions of the Code, controlled foreign corporations, foreign controlled foreign corporations, passive foreign investment companies and certain former U.S. citizens or long-term residents.

In addition, this discussion does not address the tax treatment of partnerships (or entities or arrangements that are treated as partnerships or disregarded entities for U.S. federal income tax purposes) or persons that hold our securities through such partnerships. If a partnership, including any entity or arrangement treated as a partnership for U.S. federal income tax purposes, holds our securities, the U.S. federal income tax treatment of a partner in such partnership will generally depend upon the status of the partner and the activities of the partnership. Such partners and partnerships should consult their tax advisors regarding the tax consequences of the purchase, ownership and disposition of our securities.

Allocation of Purchase Price

Each purchaser of Shares must allocate its purchase price for such Shares between each Share and purchase warrant based on the respective relative fair market values of each at the time of issuance. This allocation of the purchase price will establish the holder’s initial tax basis for U.S. federal income tax purposes for each Share and purchase warrant. A holder’s allocation of the purchase price among the

S-17

TABLE OF CONTENTS

Shares and purchase warrants is not binding on the IRS or the courts, and no assurance can be given that the IRS or the courts will agree with a holder’s allocation. Each holder should consult its own tax advisor regarding the allocation of the purchase price among the Shares and purchase warrants.

Tax Considerations Applicable to U.S. Holders

Definition of U.S. Holder

In general, a “U.S. holder” means a beneficial owner of our securities (other than a partnership or an entity or arrangement treated as a partnership for U.S. federal income tax purposes) that is, for U.S. federal income tax purposes:

•

an individual who is a citizen or resident of the United States;

​

•

a corporation, or an entity treated as a corporation for U.S. federal income tax purposes, created or organized in the United States or under the laws of the United States or of any state thereof or the District of Columbia;

​

•

an estate, the income of which is subject to U.S. federal income tax regardless of its source; or

​

•

a trust if  (a) a U.S. court can exercise primary supervision over the trust’s administration and one or more U.S. persons have the authority to control all of the trust’s substantial decisions or (b) the trust has a valid election in effect under applicable U.S. Treasury Regulations to be treated as a U.S. person.

​

Exercise of Purchase Warrants

A U.S. holder generally will not recognize gain or loss on the exercise of a purchase warrant and the related receipt of warrant shares (unless cash is received in lieu of the issuance of a fractional warrant share). A U.S. holder’s initial tax basis in a warrant share will be equal to the sum of  (a) such U.S. holder’s tax basis in the purchase warrant plus (b) the exercise price paid by such U.S. holder on the exercise of such purchase warrant. A U.S. holder’s holding period in a warrant share received on the exercise of a purchase warrant generally should begin on the day after the date that such purchase warrant is exercised by such U.S. holder.

In certain circumstances, the purchase warrants may be exercised on a cashless basis. The U.S. federal income tax treatment of an exercise of a warrant on a cashless basis is not clear, and could differ from the consequences described above. It is possible that a cashless exercise could be a taxable event. U.S. holders are urged to consult their tax advisors as to the consequences of an exercise of a purchase warrant on a cashless basis, including with respect to their holding period and tax basis in the warrant share.

Distributions on the Shares or the Warrant Shares

We do not anticipate declaring or paying any future distributions. However, if we do make distributions on the Shares or the warrant shares, such distributions will constitute dividends to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles, and will be includible in your income as ordinary income when received. However, with respect to dividends received by individuals, such dividends are generally taxed at the lower applicable long-term capital gains rates, provided certain holding period and other requirements are satisfied. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the U.S. holder’s investment, up to such U.S. holder’s adjusted tax basis in the Shares or the warrant shares, as applicable. Any remaining excess will be treated as capital gain from the sale or exchange of such Shares or warrant shares, subject to the tax treatment described in “—Sale or Other Taxable Disposition of the Shares Purchase Warrants or Warrant Shares.”

Sale or Other Taxable Disposition of the Shares Purchase Warrants or Warrant Shares

Upon the sale, exchange or other taxable disposition of the Shares, purchase warrants (other than by exercise) or warrant shares, a U.S. holder will generally recognize capital gain or loss equal to the difference between the amount of cash and the fair market value of any property received upon the sale, exchange or other taxable disposition and such U.S. holder’s adjusted tax basis in the Shares purchase warrants or warrant shares. This capital gain or loss will be long-term capital gain or loss if the U.S. holder’s holding period in such Shares purchase warrants or warrant shares is more than one year at the time of the sale,

S-18

TABLE OF CONTENTS

exchange or other taxable disposition. Long-term capital gains recognized by certain non-corporate U.S. holders, including individuals, generally will be subject to reduced rates of U.S. federal income tax. The deductibility of capital losses is subject to certain limitations.

Lapse of Purchase Warrants

Upon the lapse or expiration of a purchase warrant, a U.S. holder will recognize a loss in an amount equal to such U.S. holder’s tax basis in the purchase warrant. Any such loss generally will be a capital loss and will be long-term capital loss if the purchase warrant is held for more than one year. Deductions for capital losses are subject to limitations.

Certain Adjustments to the Purchase Warrants

The terms of each purchase warrant provide for an adjustment to the number of warrant shares for which the purchase warrant may be exercised and/or to the exercise price of the purchase warrant in certain events. An adjustment to the exercise price of a purchase warrant may be treated as a constructive distribution to a U.S. holder of the purchase warrants depending on the circumstances of such adjustment if, and to the extent that, such adjustment has the effect of increasing such U.S. holder’s proportionate interest in our “earnings and profits” or assets, depending on the circumstances of such adjustment. In addition, the failure to provide for such an adjustment (or to adequately adjust) may also result in a deemed distribution to U.S. holders of the purchase warrants or Shares. Any such constructive distribution may be taxable whether or not there is an actual distribution of cash or other property. However, adjustments to the exercise price of purchase warrants made pursuant to a bona fide reasonable adjustment formula that has the effect of preventing dilution of the interest of the holders thereof generally should not be considered to result in a constructive distribution. Generally, such deemed distributions will be taxable in the same manner as an actual distribution as described in “—Distributions on the Shares or the Warrant Shares,” except that it is unclear whether such deemed distributions would be eligible for the reduced tax rate applicable to certain dividends paid to non-corporate holders or the dividend-received deduction applicable to certain dividends paid to corporate holders. Generally, a U.S. holder’s tax basis in the underlying stock will be increased to the extent any such constructive distribution is treated as a dividend. Proposed U.S. Treasury Regulations address the amount of, timing of, and withholding obligations in respect to, constructive distributions made to holders of convertible securities such as the purchase warrants. These proposed regulations are effective for constructive distributions made on or after the date of finalization, but may generally be relied upon as to certain matters for constructive distributions that occur prior to such date. U.S. holders should consult their own tax advisors regarding the application of such regulations and other tax considerations relating to the possibility of constructive distributions.

Backup Withholding and Information Reporting

A U.S. holder may be subject to information reporting and backup withholding when such holder receives payments on our securities (including constructive dividends) or receives proceeds from the sale or other taxable disposition of our securities. Certain U.S. holders are exempt from backup withholding, including C corporations and certain tax-exempt organizations. A U.S. holder will be subject to backup withholding if such holder is not otherwise exempt and such holder:

•

fails to furnish the holder’s taxpayer identification number, which for an individual is ordinarily his or her social security number;

​

•

furnishes an incorrect taxpayer identification number;

​

•

is notified by the IRS that the holder previously failed to properly report payments of interest or dividends; or

​

•

fails to certify under penalties of perjury that the holder has furnished a correct taxpayer identification number and that the IRS has not notified the holder that the holder is subject to backup withholding.

​

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS. U.S. holders should consult their tax advisors regarding their qualification for an exemption from backup withholding and the procedures for obtaining such an exemption.

S-19

TABLE OF CONTENTS

Tax Considerations Applicable to Non-U.S. Holders

Definition of non-U.S. Holder

For purposes of this discussion, a “non-U.S. holder” is a beneficial owner of our securities that is neither a U.S. holder nor a partnership or an entity or arrangement treated as a partnership for U.S. federal income tax purposes.

Exercise of Purchase Warrants

A non-U.S. holder generally will not recognize gain or loss on the exercise of a purchase warrant and the related receipt of warrant shares (unless cash is received in lieu of the issuance of a fractional warrant share and certain other conditions are present, as discussed under “—Gain on Sale, Exchange or Other Taxable Disposition of Our Securities”). See “—Tax Considerations Applicable to U.S. Holders—Exercise of Purchase Warrants.” However, if a cashless exercise of purchase warrants results in a taxable exchange, as described in “—Tax Considerations Applicable to U.S. Holders—Exercise of Purchase Warrants,” the rules described in “Gain on Sale, Exchange or Other Taxable Disposition of Our Securities” would apply.

Lapse of Purchase Warrants

If a non-U.S. holder allows a purchase warrant to expire unexercised, such non-U.S. holder will recognize a capital loss in an amount equal to such holder’s tax basis in the purchase warrant. See “—Tax Considerations Applicable to U.S. Holders—Lapse of Warrants.”

Certain Adjustments to the Purchase Warrants

See the discussion of the rules applicable to constructive distributions on a purchase warrant in “—Tax Considerations Applicable to U.S. Holders—Certain Adjustments to the Warrants.” If an adjustment to the number of warrant shares that will be issued on the exercise of the purchase warrants, or an adjustment to the exercise price of the purchase warrants, results in a constructive distribution, as described in “—Tax Considerations Applicable to U.S. Holders—Certain Adjustments to the Purchase Warrants,” the rules described in “—Distributions on the Shares or the Warrant Shares” would apply. U.S. federal income tax required to be withheld on any portion of such constructive distribution that is treated as a dividend (as described in “—Distributions on the Shares or the Warrant Shares”) may be withheld from warrant shares, sales proceeds subsequently paid or credited, or other amounts payable or distributable to a non-U.S. holder.

Distributions on the Shares or the Warrant Shares

We do not anticipate declaring or paying any future distributions. However, if we make distributions on the Shares or the warrant shares such distributions will constitute dividends to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder’s investment, up to such non-U.S. holder’s adjusted tax basis in the Shares or the warrant shares, as applicable. Any remaining excess will be treated as capital gain from the sale or exchange of such Shares or warrant shares, subject to the tax treatment described in “—Gain on Sale, Exchange or Other Taxable Disposition of Our Securities” below.

Dividends paid to a non-U.S. holder will generally be subject to withholding of U.S. federal income tax at a 30% rate of the gross amount of the dividend or such lower rate as may be specified by an applicable income tax treaty between the United States and such non-U.S. holder’s country of residence for purposes of such treaty.

Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if the non-U.S. holder satisfies applicable certification and disclosure requirements. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same U.S. federal income tax rates applicable to U.S. persons (as defined in the Code). Any U.S. effectively connected income received by a non-U.S. holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or

S-20

TABLE OF CONTENTS

such lower rate as may be specified by an applicable income tax treaty between the United States and such non-U.S. holder’s country of residence for purposes of such treaty.

To claim a reduction or exemption from withholding, a non-U.S. holder generally will be required to provide (a) a properly executed IRS Form W-8BEN or IRS Form W-8BEN-E (or successor form) and satisfy applicable certification and other requirements to claim the benefit of an applicable income tax treaty between the United States and such non-U.S. holder’s country of residence, or (b) a properly executed IRS Form W-8ECI stating that dividends are not subject to withholding because they are effectively connected with such non-U.S. holder’s conduct of a trade or business within the United States. Non-U.S. holders are urged to consult their tax advisors regarding their entitlement to benefits under a relevant income tax treaty.

A non-U.S. holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

Distributions will also be subject to the discussion in “—Backup Withholding and Information Reporting” and “—Foreign Accounts.”

Gain on Sale, Exchange or Other Taxable Disposition of Our Securities

Subject to the discussion in “—Backup Withholding and Information Reporting” and “—Foreign Accounts,” in general, a non-U.S. holder will not be subject to any U.S. federal income tax on any gain realized upon such non-U.S. holder’s sale, exchange or other taxable disposition of our securities unless:

•

the gain is effectively connected with a U.S. trade or business of the non-U.S. holder and, if an applicable income tax treaty so provides, is attributable to a permanent establishment or a fixed base maintained in the United States by such non-U.S. holder, in which case the non-U.S. holder generally will be taxed at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code) and, if the non-U.S. holder is a foreign corporation, the branch profits tax described in “—Distributions on the Shares or the Warrant Shares” also may apply;

​

•

the non-U.S. holder is a nonresident alien individual who is present in the United States for 183 days or more in the taxable year of the disposition and certain other conditions are met, in which case the non-U.S. holder will be subject to a 30% U.S. federal income tax (or such lower rate as may be specified by an applicable income tax treaty) on the net gain derived from the disposition, which may be offset by U.S. source capital losses of the non-U.S. holder, if any (even though the individual is not considered a resident of the United States); or

​

•

we are, or have been, at any time during the five-year period preceding such disposition (or the non-U.S. holder’s holding period, if shorter) a “U.S. real property holding corporation” in which case such non-U.S. holder generally will be taxed on its net gain derived from the disposition as effectively connected income taxable at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code); however, the branch profits tax described above will not apply to a U.S. holder that is a foreign corporation. Generally, a corporation is a U.S. real property holding corporation if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. Although there can be no assurance, we do not believe that we are, or have been, a U.S. real property holding corporation, or that we are likely to become one in the future. Even if we are or become a U.S. real property holding corporation, provided that our common stock is regularly traded, as defined by applicable U.S. Treasury Regulations, on an established securities market, the Shares will be treated as a U.S. real property interest only with respect to a non-U.S. holder that holds more than 5% of our outstanding common stock, directly or indirectly, actually or constructively, during the shorter of the 5-year period ending on the date of the disposition or the period that the non-U.S. holder held the Shares or warrant shares, as applicable. There can be no assurance that our common stock will continue to qualify as regularly traded on an established securities market. Disposition by a non-U.S. holder of purchase warrants (that are not expected to be regularly traded on an established securities market) may also be eligible for an exemption from withholding even if we are treated as a U.S. real property holding corporation, if on the date such purchase warrants were acquired by such

​

S-21

TABLE OF CONTENTS

non-U.S. holder such holdings had a fair market value no greater than the fair market value on that date of 5% of our regularly-traded common stock, provided that, if a non-U.S. holder holding our not-regularly-traded purchase warrants subsequently acquires additional purchase warrants, then such interests would be aggregated and valued as of the date of the subsequent acquisition to apply this 5% limitation.

Backup Withholding and Information Reporting

We must report annually to the IRS and to each non-U.S. holder the gross amount of the distributions on our securities paid to such non-U.S. holder and the tax withheld, if any, with respect to such distributions. Non-U.S. holders will have to comply with specific certification procedures to establish that the holder is not a U.S. person (as defined in the Code) in order to avoid backup withholding at the applicable rate with respect to any dividends on our securities. A non-U.S. holder generally will not be subject to U.S. backup withholding with respect to payments of dividends on our securities if it certifies its non-U.S. status by providing a valid IRS Form W-8BEN or IRS Form W-8BEN-E (or successor form) or IRS Form W-8ECI, or otherwise establishes an exemption; provided we do not have actual knowledge or reason to know such non-U.S. holder is a U.S. person, as defined in the Code. Dividends paid to non-U.S. holders subject to the U.S. withholding tax, as described in “—Distributions on the Shares or the Warrant Shares” generally will be exempt from U.S. backup withholding.

Information reporting and backup withholding will generally apply to the proceeds of a disposition of our securities by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker. Non-U.S. holders should consult their tax advisors regarding the application of the information reporting and backup withholding rules to them.

Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is established under the provisions of a specific treaty or agreement.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder may be allowed as a credit against the non-U.S. holder’s U.S. federal income tax liability, if any, and may entitle such holder to a refund, provided that the required information is timely furnished to the IRS.

Foreign Accounts

The Code generally imposes a U.S. federal withholding tax of 30% on dividends and, subject to the discussion below regarding proposed regulations issued by the U.S. Treasury Department, the gross proceeds of a disposition of our securities paid to a “foreign financial institution” ​(as defined in the Code), unless such institution enters into an agreement with the U.S. government to, among other things, withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding accounts held by certain “specific United States persons” or “United States owned foreign entities” ​(each as defined in the Code), or otherwise qualifies for an exemption from these rules. A U.S. federal withholding tax of 30% also applies to dividends and, subject to the discussion below regarding proposed regulations issued by the U.S. Treasury Department, will apply to the gross proceeds of a disposition of our securities paid to a “non-financial foreign entity” ​(as defined in the Code), unless such entity provides the withholding agent with either a certification that it does not have any “substantial United States owners” ​(as defined in the Code), provides information regarding each substantial United States owners of the entity, or otherwise qualifies for an exemption from these rules. Under certain circumstances, a non-U.S. holder might be eligible for refunds or credits of such taxes. An intergovernmental agreement between the United States and an applicable foreign country may modify the requirements described in this paragraph.

The withholding provisions described above currently apply to dividends paid on our securities. The U.S. Treasury Department released proposed regulations which, if finalized in their present form, would

S-22

TABLE OF CONTENTS

eliminate the U.S. federal withholding tax of 30% applicable to the gross proceeds of a sale or other disposition of our securities. In its preamble to such proposed regulations, the U.S. Treasury Department stated that taxpayers may generally rely on the proposed regulations until final regulations are issued.

EACH PROSPECTIVE INVESTOR SHOULD CONSULT ITS TAX ADVISOR REGARDING THE PARTICULAR U.S. FEDERAL, STATE AND LOCAL AND NON-U.S. TAX CONSEQUENCES OF PURCHASING, HOLDING AND DISPOSING OF OUR SECURITIES, INCLUDING THE CONSEQUENCES OF ANY PROPOSED CHANGE IN APPLICABLE LAWS.

S-23

TABLE OF CONTENTS​

UNDERWRITING

We and Piper Sandler & Co. and BTIG, LLC, as representatives for the underwriters named below, have entered into an underwriting agreement with respect to the shares of common stock and accompanying purchase warrants being offered hereby. Subject to the terms and conditions contained in the underwriting agreement, we have agreed to sell to the underwriters, and each underwriter has agreed to purchase, at the public offering prices less the underwriting discounts and commissions set forth on the cover page of this prospectus supplement, the number of shares of our common stock and purchase warrants set forth opposite its name in the table below.

Name

​

​

Number of Shares

​

​

Number of Purchase Warrants to Purchase Shares of Common Stock

​

Piper Sandler & Co.

​

​

​

​

37,500,000

​

​

​

​

​

37,500,000

​

​

BTIG, LLC

​

​

​

​

13,888,889

​

​

​

​

​

13,888,889

​

​

Brookline Capital Markets, a division of Arcadia Securities, LLC

​

​

​

​

4,166,667

​

​

​

​

​

4,166,667

​

​

Total

​

​

​

​

55,555,556

​

​

​

​

​

55,555,556

​

​

The obligations of the underwriters under the underwriting agreement are several and not joint. The underwriting agreement provides that the underwriters’ obligation to purchase shares of our common stock and purchase warrants depends on the satisfaction of certain conditions precedent contained in the underwriting agreement, including that the representations and warranties made by us are true and our obligations have been performed, the receipt by the underwriters of officers’ certificates and legal opinions and approval of certain legal matters by their counsel.

Subject to those conditions, the underwriters have severally agreed to purchase and pay for all such shares of common stock and purchase warrants if any are purchased. However, the underwriters are not obligated to take or pay for the shares of our common stock and purchase warrants covered by the underwriters’ purchase option described below, unless and until such option is exercised.

The shares of common stock and purchase warrants are being offered by the underwriters, subject to prior sale, when, as and if issued to and accepted by them. The underwriters reserve the right to withdraw, cancel or modify this offer and to reject orders in whole or in part. The obligations of the underwriters may also be terminated upon the occurrence of the events specified in the underwriting agreement.

Option to Purchase Additional Shares and Purchase Warrants

We have granted the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase up to an aggregate of 8,333,333 additional shares of our common stock and/or warrants to purchase up to 8,333,333 additional shares of our common stock from us at the applicable public offering price set forth on the cover page of this prospectus supplement, less underwriting discounts and commissions. If the underwriters exercise this option, each underwriter will be obligated, subject to certain conditions, to purchase a number of additional shares proportionate to that underwriter’s initial purchase commitment as indicated in the table above for which the option has been exercised.

Discounts and Expenses

The underwriters propose to offer the shares of common stock and accompanying purchase warrants to the public at the combined public offering price set forth on the cover page of this prospectus supplement and to dealers at that price less a concession not in excess of  $0.03564 per share of common stock and accompanying purchase warrant. After the offering, the public offering prices and concessions to dealers may be reduced by the underwriters.

The following table shows the combined public offering price and total underwriting discount that we will pay to the underwriters and the proceeds we will receive before expenses. These amounts are shown assuming both no exercise and full exercise of the underwriters’ option to purchase additional shares of common stock and/or purchase warrants.

S-24

TABLE OF CONTENTS

​

​

​

Per Share and Accompanying Purchase Warrant

​

​

Total Without Option Exercise

​

​

Total With Full Option Exercise

​

Public offering price

​

​

​

$

0.9900

​

​

​

​

$

55,000,000.44

​

​

​

​

$

63,250,000.11

​

​

Underwriting discounts and commissions

​

​

​

$

0.0594

​

​

​

​

$

3,300,000.03

​

​

​

​

$

3,795,000.01

​

​

Proceeds, before expenses, to us(1)

​

​

​

$

0.9306

​

​

​

​

$

51,700,000.41

​

​

​

​

$

59,455,000.10

​

​

​

(1)

The amount of the offering proceeds to us presented in this table does not give effect to the exercise, if any, of the purchase warrants.

​

We estimate that the total expenses of the offering, excluding the underwriting discounts and commissions, will be approximately $630,000. We have also agreed to reimburse the underwriters for certain of their fees and expenses of their counsel up to $125,000. In accordance with FINRA Rule 5110 these reimbursed expenses are deemed underwriting compensation for this offering.

Upon any exercise for cash of the warrants issued in this offering, we will be required to pay the underwriters a commission equal to 6.0% of the aggregate gross proceeds received upon the exercise of such warrants if and to the extent that such commission is not prohibited under the rules of the Financial Industry Regulatory Authority, including Rule 5110(g)(10).

Lock-Up Agreements

For a period of 60 days following the date of the underwriting agreement, we and our executive officers, directors and certain stockholders, collectively, the “Lock-Up Parties”, have agreed that without the prior written consent of the representatives, and subject to specified exceptions, not to:

(i)

directly or indirectly, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase or otherwise transfer or dispose of any shares of common stock or any securities convertible into or exercisable or exchangeable for common stock, collectively, the “Lock-Up Securities”, or exercise any right with respect to the registration of any of the Lock-Up Securities, or file or cause to be filed any registration statement in connection therewith, under the Securities Act, or

​

(ii)

enter into any swap or any other agreement or any transaction that transfers, in whole or in part, directly or indirectly, the economic consequence of ownership of the Lock-Up Securities, whether any such swap or transaction is to be settled by delivery of common stock or other securities, in cash or otherwise.

​

The restrictions on our actions, as described above, do not apply to (i) the shares of common stock to be sold hereunder, including the exercise of any shares of common stock upon the exercise of any purchase warrants, (ii) the issuance of shares of common stock or options to purchase shares of common stock or restricted stock units or similar equity securities, or the issuance of shares of common stock upon exercise of options, settlement of restricted stock units or similar equity securities, pursuant to any options, share bonus or other share plan or arrangement pursuant to an incentive plan of ours in effect on the date of this prospectus supplement and described in this prospectus supplement, (iii) the filing by us of a registration statement on Form S-8 in respect of any shares or other equity instruments issued pursuant to any plans or programs described above, (iv) the issuance of any shares of common stock upon the exercise of an option or warrant or upon the conversion of a convertible security outstanding on the date of this prospectus supplement and referred to in this prospectus supplement, or (v) the issuance of shares of common stock or securities convertible into or exercisable or exchangeable for common stock in connection with any acquisition, business combination, any collaboration, licensing or joint venture or other strategic transaction involving us; provided, that the aggregate number of common stock or securities convertible into or exercisable for common stock (on an as-converted or as-exercised basis, as the case may be) that we may issue or agree to issue pursuant to this clause (v) shall not exceed 5% of the total number of our common stock issued and outstanding immediately following the completion of this offering; and provided further, that each recipient of common stock or securities convertible into or exercisable for common stock pursuant to this clause (v) shall execute a lock-up agreement.

S-25

TABLE OF CONTENTS

The restrictions described above do not apply to our directors or officers with respect to transfers of common stock:

(i)

as a bona fide gift or gifts including a bona fide gift or gifts to a charitable organization or educational institution;

​

(ii)

to the immediate family of the Lock-Up Party or any trust or other entity for the direct or indirect benefit of the Lock-Up Party or the immediate family of the Lock-Up Party (for purposes hereof, “immediate family” shall mean any relationship by blood, marriage or adoption, not more remote than first cousin);

​

(iii)

as a distribution or other transfer to limited or general partners, stockholders or other equity holders of the Lock-Up Party;

​

(iv)

to the Lock-Up Party’s affiliates or to any investment fund or other entity controlled or managed by the Lock-Up Party;

​

(v)

by operation of law pursuant to an order of a court or a regulatory agency or pursuant to a qualified domestic relations order or in connection with a divorce settlement;

​

(vi)

by will or intestacy;

​

(vii)

to us in satisfaction with any tax withholding obligation;

​

(viii)

in transactions relating to shares of common stock acquired in this offering or in open market transactions after the completion of this offering;

​

(ix)

to us pursuant to agreements under which we have the option to repurchase such shares or a right of first refusal with respect to transfers of such shares upon termination of service of the Lock-Up Party;

​

(x)

transfers to us upon a vesting event of our securities or upon the exercise or conversion of options or warrants to purchase our securities in each case for cash or on a “cashless” or “net exercise” basis or any transfer to cover tax withholding obligations of the Lock-Up Party in connection with such vesting or exercise, pursuant to an incentive plan of ours; provided, however, that the underlying shares of common stock shall continue to be subject to the restrictions on transfer set forth in the lock-up agreement; or

​

(xi)

to a bona fide third party pursuant to a merger, consolidation, tender offer or other similar transaction made to all holders of common stock and involving a change of control and approved by our board of directors; provided that, in the event that such change of control is not completed, the Lock-Up Party’s Lock-Up Securities shall remain subject to the restrictions contained in the lock-up agreement.

​

Indemnification and Contribution

We have agreed to indemnify the underwriters, its affiliates, its selling agents, officers and directors and persons, if any, who control the underwriters, against certain liabilities, including liabilities under the Securities Act, and to contribute to payments that the underwriters may be required to make in respect of these liabilities.

Stabilization

In connection with this offering, the underwriters may engage in stabilizing transactions, over-allotment transactions, syndicate covering transactions and penalty bids.

Stabilizing transactions permit bids to purchase shares of common stock so long as the stabilizing bids do not exceed a specified maximum and are engaged in for the purpose of preventing or slowing a decline in the market price of the common stock while the offering is in progress.

Over-allotment transactions involve sales by the underwriters of shares of common stock in excess of the number of shares the underwriters are obligated to purchase. This creates a syndicate short position that may be either a covered short position or a naked short position. In a covered short position, the number of shares of common stock over-allotted by the underwriters are not greater than the number of

S-26

TABLE OF CONTENTS

shares that they may purchase in the over-allotment option described herein. In a naked short position, the number of shares involved is greater than the number of shares in the over-allotment option described herein. The underwriters may close out any short position by exercising their over-allotment option and/or purchasing shares in the open market.

Syndicate covering transactions involve purchases of common stock in the open market after the distribution has been completed in order to cover syndicate short positions. In determining the source of shares to close out the short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared with the price at which they may purchase shares through exercise of the over-allotment option. If the underwriters sell more shares than could be covered by exercise of the over-allotment option and, therefore, have a naked short position, the position can be closed out only by buying shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that after pricing there could be downward pressure on the price of the shares in the open market that could adversely affect investors who purchase in the offering.

Penalty bids permit the representative to reclaim a selling concession from a syndicate member when the common stock originally sold by that syndicate member is purchased in stabilizing or syndicate covering transactions to cover syndicate short positions. These stabilizing transactions, over-allotment transactions, syndicate covering transactions and penalty bids may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock in the open market may be higher than it would otherwise be in the absence of these transactions. Neither we nor the underwriters make any representation or prediction as to the effect that the transactions described above may have on the price of our common stock. These transactions may be effected on the Nasdaq Capital Market, in the over-the-counter market or otherwise and, if commenced, may be discontinued at any time.

The underwriters may also engage in passive market making transactions in our common stock on the Nasdaq Capital Market in accordance with Rule 103 of Regulation M during a period before the commencement of offers or sales of shares of our common stock in this offering and extending through the completion of distribution. However, the underwriters are not obligated to do so, and the underwriters may discontinue any market-making activities at any time without notice in their sole discretion. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker’s bid, that bid must then be lowered when specified purchase limits are exceeded.

Listing

Our shares of common stock are listed on The Nasdaq Capital Market under the symbol “OTLK.” The purchase warrants are not anticipated to be listed on any securities exchange or recognized trading system.

Other Activities and Relationships

The underwriters and their respective affiliates have engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us or our affiliates and have received, or may in the future receive, customary fees and commissions for these transactions.

In addition, in the ordinary course of their business activities, the underwriters and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. The underwriters and their respective affiliates may make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Electronic Distribution

A prospectus supplement in electronic format may be made available by e-mail or on the websites or through online services maintained by one or more of the underwriters or their affiliates. In those cases, prospective investors may view offering terms online and may be allowed to place orders online. The

S-27

TABLE OF CONTENTS

underwriters may agree with us to allocate a specific number of shares of our common stock for sale to online brokerage account holders. Any such allocation for online distributions will be made by the underwriters on the same basis as other allocations. Other than this prospectus supplement in electronic format, the information on the underwriters’ websites and any information contained on any other website maintained by the underwriters is not part of this prospectus supplement, has not been approved and/or endorsed by the underwriters or us and should not be relied upon by investors.

Selling Restrictions

Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the securities offered by this prospectus supplement and the accompanying prospectus in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement and the accompanying prospectus may not be offered or sold, directly or indirectly, nor may this prospectus supplement, the accompanying prospectus or any other offering material or advertisements in connection with the offer and sale of any such securities, or any documents incorporated by reference herein, be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement or the accompanying prospectus comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement and the accompanying prospectus. This prospectus supplement and the accompanying prospectus, including any documents incorporated by reference herein, does not constitute an offer to sell or a solicitation of an offer to buy the securities offered by this prospectus supplement and the accompanying prospectus in any jurisdiction in which such an offer or a solicitation is unlawful.

Notice to Prospective Investors in the European Economic Area

In relation to each Member State of the European Economic Area (each a Relevant State), no securities have been offered or will be offered pursuant to the offering to the public in that Relevant State prior to the publication of a prospectus in relation to the securities which has been approved by the competent authority in that Relevant State or, where appropriate, approved in another Relevant State and notified to the competent authority in that Relevant State, all in accordance with the Prospectus Regulation, except that offers of common stock may be made to the public in that Relevant State at any time under the following exemptions under the Prospectus Regulation:

(a)

to any legal entity which is a qualified investor as defined under Article 2 of the Prospectus Regulation;

​

(b)

to fewer than 150 natural or legal persons (other than qualified investors as defined under Article 2 of the Prospectus Regulation), subject to obtaining the prior consent of the underwriter; or

​

(c)

in any other circumstances falling within Article 1(4) of the Prospectus Regulation,

​

provided that no such offer of securities shall require us or any underwriter to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation and each person who initially acquires any securities or to whom any offer is made will be deemed to have represented, acknowledged and agreed to and with the underwriter and the Company that it is a “qualified investor” within the meaning of Article 2(e) of the Prospectus Regulation. In the case of any securities being offered to a financial intermediary as that term is used in the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged and agreed that the securities acquired by it in the offer have not been acquired on a non-discretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer of any securities to the public other than their offer or resale in a Relevant State to qualified investors as so defined or in circumstances in which the prior consent of the underwriter has been obtained to each such proposed offer or resale.

For the purposes of this provision, the expression an “offer to the public” in relation to the securities in any Relevant State means the communication in any form and by any means of sufficient information on the terms of the offer and any securities to be offered so as to enable an investor to decide to purchase or subscribe for any securities, and the expression “Prospectus Regulation” means Regulation (EU) 2017/1129.

S-28

TABLE OF CONTENTS

Notice to Prospective Investors in the United Kingdom

In relation to the United Kingdom, no securities have been offered or will be offered pursuant to the offering to the public in the United Kingdom prior to the publication of a prospectus in relation to the securities that either have been approved by the Financial Conduct Authority or is to be treated as if it had been approved by the Financial Conduct Authority in accordance with the transitional provisions in Article 74 (transitional provisions) of the Prospectus Amendment etc (EU Exit) Regulations 2019/1234, except that the securities may be offered to the public in the United Kingdom at any time:

(a)

to any legal entity which is a qualified investor as defined under Article 2 of the UK Prospectus Regulation;

​

(b)

to fewer than 150 natural or legal persons (other than qualified investors as defined under Article 2 of the UK Prospectus Regulation), subject to obtaining the prior consent of the underwriter for any such offer; or

​

(c)

in any other circumstances falling within Section 86 of the Financial Services and Markets Act 2000 (the FSMA).

​

provided that no such offer of the securities shall require us or any underwriter to publish a prospectus pursuant to Section 85 of the FSMA or supplement a prospectus pursuant to Article 23 of the UK Prospectus Regulation. For the purposes of this provision, the expression an “offer to the public” in relation to the securities in the United Kingdom means the communication in any form and by any means of sufficient information on the terms of the offer and any securities to be offered so as to enable an investor to decide to purchase or subscribe for any securities and the expression “UK Prospectus Regulation” means Regulation (EU) 2017/1129 as it forms part of domestic law by virtue of the European Union (Withdrawal) Act 2018.

In addition, in the United Kingdom, this document is being distributed only to, and is directed only at, and any offer subsequently made may only be directed at persons who are “qualified investors” ​(as defined in the Prospectus Regulation) (i) who have professional experience in matters relating to investments falling within Article 19(5) of the FSMA (Financial Promotion) Order 2005, as amended (the Order) and/or (ii) who are high net worth companies (or persons to whom it may otherwise be lawfully communicated) falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as “relevant persons”) or otherwise in circumstances which have not resulted and will not result in an offer to the public of the securities in the United Kingdom within the meaning of the FSMA.

Any person in the United Kingdom that is not a relevant person should not act or rely on the information included in this document or use it as basis for taking any action. In the United Kingdom, any investment or investment activity that this document relates to may be made or taken exclusively by relevant persons.

Notice to Prospective Investors in Canada

The securities may be sold in Canada only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the securities must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriter is not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

S-29

TABLE OF CONTENTS

Notice to Prospective Investors in Switzerland

This prospectus supplement does not constitute an offer to the public or a solicitation to purchase or invest in any securities. No securities have been offered or will be offered to the public in Switzerland, except that offers of our common stock may be made to the public in Switzerland at any time under the following exemptions under the Swiss Financial Services Act, or FinSA:

(a)

to any person which is a professional client as defined under the FinSA;

​

(b)

to fewer than 500 persons (other than professional clients as defined under the FinSA), subject to obtaining the prior consent of the underwriter for any such offer; or

​

(c)

in any other circumstances falling within Article 36 FinSA in connection with Article 44 of the Swiss Financial Services Ordinance,

​

provided that no such offer of securities shall require the Company or any investment bank to publish a prospectus pursuant to Article 35 FinSA.

The securities have not been and will not be listed or admitted to trading on a trading venue in Switzerland.

Neither this document nor any other offering or marketing material relating to the securities constitutes a prospectus as such term is understood pursuant to the FinSA and neither this document nor any other offering or marketing material relating to the securities may be publicly distributed or otherwise made publicly available in Switzerland.

Notice to Prospective Investors in the Dubai International Financial Centre, or DIFC

This document relates to an Exempt Offer in accordance with the Markets Law, DIFC Law No.1 of 2012, as amended. This document is intended for distribution only to persons of a type specified in the Markets Law, DIFC Law No.1 of 2012, as amended. It must not be delivered to, or relied on by, any other person. The Dubai Financial Services Authority (DFSA) has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for this document. The securities to which this document relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the securities offered should conduct their own due diligence on the securities. If you do not understand the contents of this document, you should consult an authorized financial advisor.

In relation to its use in the DIFC, this document is strictly private and confidential and is being distributed to a limited number of investors and must not be provided to any person other than the original recipient, and may not be reproduced or used for any other purpose. The interests in the securities may not be offered or sold directly or indirectly to the public in the DIFC.

Notice to Prospective Investors in Australia

This prospectus supplement:

•

does not constitute a disclosure document or a prospectus under Chapter 6D.2 of the Corporations Act 2001 (Cth) (the Corporations Act);

​

•

has not been, and will not be, lodged with the Australian Securities and Investments Commission, or ASIC, as a disclosure document for the purposes of the Corporations Act and does not purport to include the information required of a disclosure document for the purposes of the Corporations Act; and

​

•

may only be provided in Australia to select investors who are able to demonstrate that they fall within one or more of the categories of investors, available under section 708 of the Corporations Act (Exempt Investors).

​

The securities may not be directly or indirectly offered for subscription or purchased or sold, and no invitations to subscribe for or buy the securities may be issued, and no draft or definitive offering memorandum, advertisement or other offering material relating to any securities may be distributed in Australia, except where disclosure to investors is not required under Chapter 6D of the Corporations Act or is otherwise in compliance with all applicable Australian laws and regulations. By submitting an application for the securities, you represent and warrant to us that you are an Exempt Investor.

S-30

TABLE OF CONTENTS

As any offer of securities under this document will be made without disclosure in Australia under Chapter 6D.2 of the Corporations Act, the offer of those securities for resale in Australia within 12 months may, under section 707 of the Corporations Act, require disclosure to investors under Chapter 6D.2 if none of the exemptions in section 708 applies to that resale. By applying for the securities, you undertake to us that you will not, for a period of 12 months from the date of sale of the securities, offer, transfer, assign or otherwise alienate those securities to investors in Australia except in circumstances where disclosure to investors is not required under Chapter 6D.2 of the Corporations Act or where a compliant disclosure document is prepared and lodged with ASIC.

Notice to Prospective Investors in Hong Kong

The securities have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than

(a)

to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571 of the Laws of Hong Kong) (the SFO) of Hong Kong and any rules made thereunder; or

​

(b)

in other circumstances which do not result in the document being a “prospectus” as defined in the Companies (Winding Up and Miscellaneous Provisions) Ordinance (Cap. 32) of Hong Kong) (the CO) or which do not constitute an offer to the public within the meaning of the CO.

​

No advertisement, invitation or document relating to the securities has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to shares of common stock which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the SFO and any rules made thereunder.

Notice to Prospective Investors in Japan

The securities have not been and will not be registered pursuant to Article 4, Paragraph 1 of the Financial Instruments and Exchange Act. Accordingly, none of the securities nor any interest therein may be offered or sold, directly or indirectly, in Japan or to, or for the benefit of, any “resident” of Japan (which term as used herein means any person resident in Japan, including any corporation or other entity organized under the laws of Japan), or to others for re-offering or resale, directly or indirectly, in Japan or to or for the benefit of a resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the Financial Instruments and Exchange Act and any other applicable laws, regulations and ministerial guidelines of Japan in effect at the relevant time.

Notice to Prospective Investors in Singapore

This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, the securities have not been offered or sold or caused to be made the subject of an invitation for subscription or purchase and will not be offered or sold or caused to be made the subject of an invitation for subscription or purchase, and this prospectus supplement or any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the securities, has not been circulated or distributed, nor will it be circulated or distributed, whether directly or indirectly, to any person in Singapore other than (i) to an institutional investor (as defined in Section 4A of the Securities and Futures Act (Chapter 289) of Singapore, as modified or amended from time to time, or the SFA) pursuant to Section 274 of the SFA, (ii) to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions specified in Section 275 of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA. Where the securities are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

(a)

a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or

​

(b)

a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor,

​

S-31

TABLE OF CONTENTS

securities or common stock-based derivatives contracts (each term as defined in Section 2(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the securities pursuant to an offer made under Section 275 of the SFA except:

(a)

to an institutional investor or to a relevant person, or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA;

​

(b)

where no consideration is or will be given for the transfer;

​

(c)

where the transfer is by operation of law;

​

(d)

as specified in Section 276(7) of the SFA; or

​

(e)

as specified in Regulation 32 of the Securities and Futures (Offers of Investments) (Shares and Debentures) Regulations of 2005 of Singapore (Regulation 32).

​

(f)

Singapore SFA product classification. In connection with Section 309B of the SFA and the CMP Regulations 2018, unless otherwise specified before an offer of securities, we have determined, and hereby notify all relevant persons (as defined in Section 309A(1) of the SFA), that the securities are “prescribed capital markets products” ​(as defined in the CMP Regulations 2018) and Excluded Investment Products (as defined in MAS Notice SFA 04-N12: Notice on the Sale of Investment Products and MAS Notice FAA-N16: Notice on Recommendations on Investment Products).

​

S-32

TABLE OF CONTENTS​​​​

LEGAL MATTERS

The validity of the securities being offered by this prospectus supplement will be passed upon for us by Cooley LLP, Chicago, Illinois. The underwriters are being represented by Paul Hastings LLP, New York, New York with respect to US federal law.

EXPERTS

The consolidated financial statements of Outlook Therapeutics, Inc. as of September 30, 2025 and 2024, and for each of the years in the two-year period ended September 30, 2025, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the September 30, 2025 consolidated financial statements contains an explanatory paragraph that states that the Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit, that raise substantial doubt about its ability to continue as a going concern. The consolidated financial statements do not include any adjustments that might result from the outcome of that uncertainty.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 we filed with the SEC under the Securities Act and do not contain all the information set forth or incorporated by reference in the registration statement. Whenever a reference is made in this prospectus supplement or the accompanying prospectus to any of our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference into this prospectus supplement and the accompanying prospectus for a copy of such contract, agreement or other document. Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the internet at the SEC’s website at www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at http://www.outlooktherapeutics.com. Our website is not a part of this prospectus supplement and is not incorporated by reference in this prospectus supplement.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus supplement and the accompanying prospectus. Information in this prospectus supplement supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus supplement, while information that we file later with the SEC will automatically update and supersede the information in this prospectus supplement and the accompanying prospectus. We incorporate by reference the documents listed below and any future filings (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items unless such Form 8-K expressly provides to the contrary) we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus supplement and prior to the termination of the offering of the common stock covered by this prospectus supplement (Commission File No. 001-37759). Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements:

•

our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, including the information specifically incorporated by reference therein from our Definitive Proxy Statement on Schedule 14A filed with the SEC on January 26, 2026;

​

•

our Quarterly Reports on Form 10-Q for the quarters ended December 31, 2025, filed with the SEC on February 17, 2026 and March 31, 2026, filed with the SEC on May 15, 2026;

​

•

our Current Reports on Form 8-K, filed with the SEC on November 3, 2025, November 13, 2025, January 2, 2026, February 11, 2026, February 18, 2026, March 5, 2026, March 10, 2026,

​

S-33

TABLE OF CONTENTS

March 11, 2026, March 16, 2026, March 25, 2026, April 7, 2026, April 21, 2026, April 23, 2026, May 13, 2026, May 26, 2026, May 28, 2026, May 29, 2026, June 1, 2026, June 16, 2026, June 26, 2026, July 16, 2026, July 24, 2026, July 24, 2026 and August 12, 2026 to the extent the information in such reports is filed and not furnished; and

•

the description of our common stock set forth in our registration statement on Form 8-A, filed with the SEC on April 29, 2016, as amended on May 11, 2016, including any further amendments thereto or reports filed for the purposes of updating this description, including Exhibit 4.1 of our Annual Report on Form 10-K.

​

We will furnish without charge to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request, a copy of any or all of the documents incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to Outlook Therapeutics, Inc., Attention: Corporate Secretary, 111 S. Wood Avenue, Unit #100, Iselin, New Jersey 08830. Our phone number is (609) 619-3990. You may also view the documents that we file with the SEC and incorporate by reference in this prospectus on our corporate website at www.outlooktherapeutics.com. The information on our website is not incorporated by reference and is not a part of this prospectus.

S-34

TABLE OF CONTENTS

PROSPECTUS

$300,000,000

Common Stock
Preferred Stock
Debt Securities
Warrants

From time to time, we may offer up to $300,000,000 of any combination of shares of our common stock, shares of our preferred stock, debt securities and warrants to purchase any of such securities, in one or more offerings as described in this prospectus. We may also offer securities as may be issuable upon conversion, redemption, repurchase, exchange or exercise of any securities registered hereunder, including any applicable antidilution provisions.

This prospectus provides a general description of the securities we may offer. Each time we offer securities, we will provide specific terms of the securities offered in a supplement to this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before you invest in any of the securities being offered.

This prospectus may not be used to consummate a sale of securities unless accompanied by a prospectus supplement.

We may sell these securities directly to investors, through agents designated from time to time or to or through underwriters or dealers, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section titled “Plan of Distribution” in this prospectus and in the applicable prospectus supplement. If any agents or underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such agents or underwriters and any applicable fees, discounts or commissions and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Our common stock is listed on The Nasdaq Capital Market under the trading symbol “OTLK.” On March 27, 2024, the last reported sale price of our common stock on The Nasdaq Capital Market was $9.37 per share. The applicable prospectus supplement will contain information, where applicable, as to other listings, if any, on The Nasdaq Capital Market or other securities exchange of the securities covered by the applicable prospectus supplement.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” on page 7 of this prospectus and any similar section contained in the applicable prospectus supplement and in any related free writing prospectuses we have authorized for use in connection with a specific offering, and under similar headings in the documents that are incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is April 5, 2024.

TABLE OF CONTENTS​

TABLE OF CONTENTS

​	​	​	Page				​
ABOUT THIS PROSPECTUS	​	​	​	​	ii	​	​
PROSPECTUS SUMMARY	​	​	​	​	1	​	​
THE SECURITIES WE MAY OFFER	​	​	​	​	4	​	​
RISK FACTORS	​	​	​	​	7	​	​
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	​	​	​	​	8	​	​
USE OF PROCEEDS	​	​	​	​	10	​	​
DESCRIPTION OF CAPITAL STOCK	​	​	​	​	11	​	​
DESCRIPTION OF DEBT SECURITIES	​	​	​	​	16	​	​
DESCRIPTION OF WARRANTS	​	​	​	​	22	​	​
LEGAL OWNERSHIP OF SECURITIES	​	​	​	​	24	​	​
PLAN OF DISTRIBUTION	​	​	​	​	27	​	​
LEGAL MATTERS	​	​	​	​	29	​	​
EXPERTS	​	​	​	​	29	​	​
WHERE YOU CAN FIND MORE INFORMATION	​	​	​	​	29	​	​
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	​	​	​	​	30	​	​

i

TABLE OF CONTENTS​

ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or SEC, utilizing a “shelf” registration process. Under this shelf registration process, we may offer and sell any combination of the securities described in this prospectus in one or more offerings up to a total aggregate offering price of  $300,000,000. This prospectus provides you with a general description of the securities we may offer.

Each time we offer and sell securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change information contained in this prospectus or in any documents that we have incorporated by reference into this prospectus. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or free writing prospectus, you should rely on the prospectus supplement or free writing prospectus, as applicable. You should read this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described under the heading “Incorporation of Certain Information by Reference,” before investing in any of the securities offered.

THIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Neither we, nor any agent, underwriter or dealer has authorized any person to give any information or to make any representation other than those contained or incorporated by reference into this prospectus, any applicable prospectus supplement or any related free writing prospectus prepared by or on behalf of us or to which we have referred you. This prospectus, any applicable supplement to this prospectus or any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus, any applicable supplement to this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.

You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered, or securities are sold, on a later date.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find More Information.”

This prospectus contains and incorporates by reference market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Information that is based on estimates, forecasts, projections, market research, or similar methodologies is inherently subject to uncertainties and involves a number of assumptions and limitations; as a result, actual events or circumstances may differ materially from events and circumstances that are assumed in this information. The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described under the heading “Risk Factors.” Although we are responsible for all of the disclosure contained in this prospectus and we believe that the data we use from third parties are reliable, we have not separately verified this data. Further, while we believe that our internal research is reliable, such research has not been verified by any third party. You are cautioned not to give undue weight to any such information, projections, and estimates.

ii

TABLE OF CONTENTS

Except as otherwise indicated or unless the context otherwise requires, references to “company,” “we,” “us,” “our” or “Outlook Therapeutics,” refer to Outlook Therapeutics, Inc. and its consolidated subsidiaries.

Our name “Outlook Therapeutics,” the Outlook Therapeutics logo and other trademarks or service marks of Outlook Therapeutics, Inc. appearing in this prospectus and in any prospectus supplement or free writing prospectus and the information incorporated by reference herein or therein are the property of Outlook Therapeutics, Inc. Other trademarks, service marks or trade names appearing in this prospectus in any prospectus supplement or free writing prospectus and the information incorporated by reference herein or therein are the property of their respective owners. We do not intend our use or display of other companies’ trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of us by, these other companies.

iii

TABLE OF CONTENTS​

​

PROSPECTUS SUMMARY

This summary highlights selected information contained elsewhere in this prospectus or incorporated by reference herein and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our securities discussed under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus. You should also carefully read the information incorporated by reference into this prospectus, including our financial statements and related notes, and the exhibits to the registration statement of which this prospectus is a part, before making your investment decision.

Overview

We are a biopharmaceutical company working to launch the first ophthalmic formulation of bevacizumab approved by the U.S. Food and Drug Administration, or the FDA, for use in retinal indications. Our goal is to launch directly in the United States as the first and only approved ophthalmic bevacizumab for the treatment of wet age-related macular degeneration, or wet AMD, diabetic macular edema, or DME, and branch retinal vein occlusion, or BRVO. Our plans also include seeking approval and launching the product in the United Kingdom, Europe, Japan and other markets, either directly into those markets or through a strategic partner. If approved, we expect to receive 12 years of regulatory exclusivity in the United States and up to 10 years of market exclusivity in the European Union.

Bevacizumab is a full-length, humanized anti-VEGF (Vascular Endothelial Growth Factor) recombinant monoclonal antibody, or mAb, that inhibits VEGF and associated angiogenic activity. In March 2022, we submitted a BLA with the FDA for ONS-5010 (LYTENAVA (bevacizumab-vikg)), an investigational ophthalmic formulation of bevacizumab, which we have developed to be administered as an intravitreal injection for the treatment of wet AMD and other retinal diseases. In May 2022, we voluntarily withdrew our BLA to provide additional information requested by the FDA. We re-submitted the BLA to the FDA for ONS-5010 on August 30, 2022, and in October 2022, we received confirmation from the FDA that our BLA had been accepted for filing with a Prescription Drug User Fee Act, or PDUFA, date of August 29, 2023 for a review decision by the FDA. On August 29, 2023, we received a Complete Response Letter, or CRL, in which the FDA concluded it could not approve our BLA during this review cycle due to several chemical, manufacturing and control, or CMC, issues, open observations from pre-approval manufacturing inspections, and a lack of substantial evidence. At subsequent Type A meetings with the FDA, we learned that the FDA was also requiring the successful completion of an additional adequate and well-controlled clinical trial evaluating ONS-5010, as well as additional requested CMC data indicated in the CRL to approve ONS-5010 for use in wet AMD.

We agreed to conduct an additional adequate, and well-controlled clinical trial following discussions with the FDA in support of our BLA for ONS-5010. In December 2023, we submitted a Special Protocol Assessment, or SPA, to the FDA for this study (NORSE EIGHT) seeking confirmation that, if successful, it will address the FDA’s requirement for a second adequate and well-controlled clinical trial to support our planned resubmission of the ONS-5010 BLA. In January 2024, we received confirmation that the FDA has reviewed and agreed upon the NORSE EIGHT trial protocol pursuant to the SPA. If the NORSE EIGHT trial is successful, it would satisfy the FDA’s requirement for a second adequate and well-controlled clinical trial to address fully the clinical deficiency identified in the CRL. The first subject was enrolled in NORSE EIGHT in January 2024. In addition, through a Type A meeting and additional interactions, we have identified the approaches needed to resolve the CMC comments in the CRL. We are working to address the open items and expect to resolve these comments prior to the expected completion of NORSE EIGHT.

Separately, in October 2022 we submitted a Marketing Authorization Application, or MAA, for ONS-5010 with the European Medicines Agency, or the EMA. On December 22, 2022, our MAA was validated for review by the EMA. The MAA was submitted as a ‘full-mixed marketing authorisation application’ based on Article 8.3 of Directive 2001/83/EC. The formal review process of the MAA by the EMA’s Committee for Medicinal Products for Human Use, or CHMP, is now underway with an estimated decision date expected in the first half of calendar year 2024. ONS-5010 is our sole product candidate in active development.

​

1

TABLE OF CONTENTS

​

Our initial BLA submission for ONS-5010 in wet AMD involved three clinical trials, which we refer to as NORSE ONE, NORSE TWO and NORSE THREE. The study design for our clinical program to evaluate ONS-5010 as an ophthalmic formulation of bevacizumab was reviewed at an end of Phase 2 meeting with the FDA in April 2018, and we filed our investigational new drug application, or IND, with the FDA in the first quarter of calendar 2019. In August 2020, we reported achieving the anticipated safety and efficacy and positive proof-of-concept topline results from NORSE ONE, a clinical experience study. NORSE TWO is our pivotal Phase 3 clinical trial comparing ONS-5010 (bevacizumab-vikg) to ranibizumab (LUCENTIS). The topline results reported from NORSE TWO in August 2021 showed that ONS-5010 met the primary and key secondary endpoint for efficacy with clinically impactful change observed for treated patients. The NORSE TWO primary endpoint difference in proportion of subjects gaining at least 15 letters in Best Corrected Visual Acuity, or BCVA, score was met and was both highly statistically significant and clinically relevant. In the intent to treat, or ITT, primary dataset, the percentage of patients who gained at least 15 letters who were treated with ONS-5010, was 41.7%, and the percentage of patients who gained at least 15 letters who were treated with ranibizumab was 23.1% (p = 0.0052). The primary endpoint was also statistically significant and clinically relevant in the secondary per protocol, or PP, dataset (p = 0.04) where the percentages were almost identical, at 41.0% with ONS-5010, and 24.7% with ranibizumab. The key secondary endpoint BCVA score change from baseline to month 11 in the primary ITT dataset was also highly statistically significant and clinically relevant (p = 0.0035). A mean change of 11.2 letters in BCVA score was observed with ONS-5010, and with ranibizumab the mean change was 5.8 letters. The results were also statistically significant in the secondary PP dataset (p = 0.01) with a mean change with ONS-5010 of 11.1 letters versus 7.0 letters with ranibizumab. Additionally, the majority of ONS-5010 subjects maintained or gained BCVA during the study (defined as change from baseline in BCVA ≥ 0), with at least 80% of ONS-5010 subjects maintaining BCVA each month. Results were also positive for the remaining NORSE TWO secondary endpoints with 56.5% (p = 0.0016) of ONS-5010 subjects gaining ≥ 10 letters of vision and 68.5% (p = 0.0116) of ONS-5010 subjects gaining ≥ 5 letters of vision. NORSE THREE is an open-label safety study we conducted to ensure the adequate number of safety exposures to ONS-5010 were available for the initial ONS-5010 BLA submission with the FDA. In March 2021, we reported that the results from NORSE THREE showed a positive safety profile for ONS-5010. The NORSE BLA registration program is also being used to support our MAA submission in the European Union.

As we agreed with the FDA in the SPA, NORSE EIGHT will be a randomized, controlled, parallel-group, masked, non-inferiority study of approximately 400 newly diagnosed, wet AMD subjects randomized in a 1:1 ratio to receive 1.25 mg ONS-5010 or 0.5 mg ranibizumab intravitreal injections. Subjects will receive injections at Day 0 (randomization), Week 4, and Week 8 visits. The primary endpoint will be mean change in BCVA from baseline to week 8. The first subject was enrolled in NORSE EIGHT in January 2024. We expect NORSE EIGHT topline results and potential resubmission of the ONS-5010 BLA by the end of calendar year 2024.

Additionally, in November 2021, we began enrolling patients in our NORSE SEVEN clinical trial. The study compares the safety of ophthalmic bevacizumab in vials versus pre-filled syringes in subjects diagnosed with a retinal condition that would benefit from treatment with intravitreal injection of bevacizumab, including exudative age-related macular degeneration, DME, or BRVO. Subjects will be treated for three months, and the enrollment of subjects in the arm of the study receiving ONS-5010 in vials has been completed.

We have also received agreement from the FDA on three Special Protocol Assessments, or SPAs, for three additional registration clinical trials for our ongoing Phase 3 program for ONS-5010. The agreements reached with the FDA on these SPAs cover the protocols for NORSE FOUR, a registration clinical trial evaluating ONS-5010 to treat BRVO, and NORSE FIVE and NORSE SIX, two registration clinical trials evaluating ONS-5010 to treat DME. We intend to initiate these studies following the anticipated FDA approval of our BLA for wet AMD.

Because there are no approved bevacizumab products for the treatment of retinal diseases in the United States and other major global markets, we submitted a standard BLA, and are not using the biosimilar drug development pathway that would be required if Avastin were an approved drug for the targeted diseases. If approved, we believe ONS-5010 has potential to mitigate risks associated with off-label use of

​

2

TABLE OF CONTENTS

​

unapproved bevacizumab. In the United States, approximately 66.3% of new patient starts are off-label repackaged bevacizumab (ASRS 2022 Membership Survey Presented at ASRS NY 2022).

Risks Associated with our Business

Our business is subject to numerous risks, as described under the heading “Risk Factors” contained in the applicable prospectus supplement and in any free writing prospectuses we have authorized for use in connection with a specific offering, and under similar headings in the documents that are incorporated by reference into this prospectus.

Implications of Being a Smaller Reporting Company

We are a “smaller reporting company” as defined in the Securities Exchange Act of 1934, as amended, or the Exchange Act. As a smaller reporting company, we are eligible to take advantage of certain exemptions from disclosure requirements, including not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act and reduced disclosure obligations regarding executive compensation. We will be able to take advantage of the scaled disclosures available to smaller reporting companies for so long as our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter, or our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.

Company Information

We initially incorporated in January 2010 in New Jersey as Oncobiologics, Inc., and in October 2015, we reincorporated in Delaware by merging with and into a Delaware corporation. In November 2018, we changed our name to Outlook Therapeutics, Inc. Our headquarters are located at 485 Route 1 South, Building F, Suite 320, Iselin, New Jersey 08830, and our telephone number at that location is (609) 619-3990. Our website address is www.outlooktherapeutics.com. The information contained on, or that can be accessed through, our website is not part of, and is not incorporated by reference into this prospectus.

​

3

TABLE OF CONTENTS​

​

THE SECURITIES WE MAY OFFER

We may offer shares of our common stock and preferred stock, various series of debt securities and/or warrants to purchase any of such securities, either individually or in combination, up to a total aggregate offering price of  $300,000,000 from time to time in one or more offerings under this prospectus, together with the applicable prospectus supplement and any related free writing prospectus, at prices and on terms to be determined by market conditions at the time of the relevant offering. We may also offer common stock, preferred stock and/or debt securities upon the exercise of warrants. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

•

designation or classification;

​

•

aggregate principal amount or aggregate offering price;

​

•

maturity;

​

•

original issue discount;

​

•

rates and times of payment of interest or dividends;

​

•

redemption, conversion, exercise, exchange or sinking fund terms;

​

•

restrictive covenants;

​

•

voting or other rights;

​

•

conversion or exchange prices or rates and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;

​

•

ranking;

​

•

restrictive covenants;

​

•

voting or other rights; and

​

•

a discussion of material or special U.S. federal income tax considerations.

​

The applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in the documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

We may sell the securities directly to investors or to or through agents, underwriters, or dealers. We, and our agents, underwriters or dealers reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities to or through agents, underwriters or dealers, we will include in the applicable prospectus supplement:

•

the names of those agents, underwriters or dealers;

​

•

applicable fees, discounts and commissions to be paid to them;

​

•

details regarding over-allotment or other options, if any; and

​

•

the net proceeds to us.

​

Common Stock

We may issue shares of our common stock from time to time. Holders of our common stock are entitled to one vote per share for the election of directors and on all other matters that require stockholder approval. Subject to any preferential rights of any then outstanding preferred stock, in the event of our liquidation,

​

4

TABLE OF CONTENTS

​

dissolution or winding up, holders of our common stock are entitled to share ratably in the assets remaining after payment of liabilities and the liquidation preferences of any then outstanding preferred stock. Our common stock does not carry any preemptive rights enabling a holder to subscribe for, or receive shares of, our common stock or any other securities convertible into shares of common stock, or any redemption rights.

Preferred Stock

We may issue shares of our preferred stock from time to time, in one or more series. Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by the stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding.

If we sell any series of preferred stock under this prospectus, we will fix the designations, voting powers, preferences and rights of such series of preferred stock, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock that we are offering before the issuance of the related series of preferred stock. We urge you to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.

Debt Securities

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible debt securities will be convertible into or exchangeable for our common stock or other securities. Conversion may be mandatory or at the holder’s option and would be at prescribed conversion rates.

Any debt securities issued under this prospectus will be issued under one or more documents called indentures, which are contracts between us and a national banking association or other eligible party, as trustee. In this prospectus, we have summarized certain general features of the debt securities. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the series of debt securities being offered, as well as the complete indentures that contain the terms of the debt securities. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

Warrants

We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. In this prospectus, we have summarized certain general features of the warrants. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of warrants being offered, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants. Forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants being offered have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental warrant agreements and forms of warrant certificates will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

​

5

TABLE OF CONTENTS

​

We will evidence each series of warrants by warrant certificates that we will issue. Warrants may be issued under an applicable warrant agreement that we enter into with a warrant agent. We will indicate the name and address of the warrant agent, if applicable, in the prospectus supplement relating to the particular series of warrants being offered.

​

6

TABLE OF CONTENTS​

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully review the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in our Annual Report on Form 10-K for the fiscal year ended September 30, 2023, as updated by our subsequent annual, quarterly and other reports and documents that are incorporated by reference into this prospectus and the applicable prospectus supplement, before deciding whether to purchase any of the securities being registered pursuant to the registration statement of which this prospectus is a part. Each of the risk factors could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities, and the occurrence of any of these risks might cause you to lose all or part of your investment. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations. Please also read carefully the section below titled “Special Note Regarding Forward-Looking Statements.”

7

TABLE OF CONTENTS​

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the documents that we incorporate by reference herein, contains, and any applicable prospectus supplement or free writing prospectus including the documents we incorporate by reference therein may contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange Act, about us and our industry that involve substantial risks and uncertainties. All statements, other than statements of historical facts contained in this prospectus, including statements regarding our future financial condition, business strategy and plans, and objectives of management for future operations, are forward-looking statements. In some cases you can identify these statements by forward-looking words such as “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potentially,” “seek,” “should,” “will,” “would,” or the negative of these terms or similar expressions. These forward-looking statements include, but are not limited to, statements concerning the following:

•

the initiation, timing, progress and results of our clinical trials of our lead product candidate, ONS-5010;

​

•

our reliance on our contract manufacturing organizations and other vendors;

​

•

whether the results of our clinical trials will be sufficient to support domestic or global regulatory approvals;

​

•

our ability to obtain and maintain regulatory approval for ONS-5010 in the United States and other markets;

​

•

our expectations regarding the potential market size and the size of the patient populations for our product candidates, if approved, for commercial use;

​

•

our ability to fund our working capital requirements;

​

•

the rate and degree of market acceptance of our current and future product candidates, including our commercialization strategy and manufacturing capabilities for ONS-5010;

​

•

the implementation of our business model and strategic plans for our business and product candidates;

​

•

developments or disputes concerning our intellectual property or other proprietary rights;

​

•

our ability to maintain and establish collaborations or obtain additional funding;

​

•

our expectations regarding government and third-party payor coverage and reimbursement;

​

•

our ability to compete in the markets we serve;

​

•

the factors that may impact our financial results; and

​

•

our expectations and estimates regarding the sufficiency of our cash resources and our need for additional funding.

​

These statements reflect our current views with respect to future events and are based on assumptions and are subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. We discuss in greater detail many of these risks under the heading “Risk Factors” contained in the applicable prospectus supplement, in any free writing prospectuses we may authorize for use in connection with a specific offering, and in our most recent Annual Report on Form 10-K and in our most recent Quarterly Report on Form 10-Q, which are incorporated by reference into this prospectus in their entirety, as well as any amendments thereto reflected in subsequent filings with the SEC. These risks are not exhaustive. Additional factors could harm our business and financial performance, such as risks associated with the current macroeconomic environment, including as a result of the impacts of inflation, high interest rates, current or potential future bank failures or ongoing overseas conflict. Moreover, we operate in a very competitive and rapidly changing environment. New risk factors emerge from time to time, and it is not possible for our management to predict all risk factors, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in, or implied by, any forward-looking statements.

8

TABLE OF CONTENTS

Forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. You should read this prospectus, any applicable prospectus supplement, together with the documents we have filed with the SEC that are incorporated by reference and any free writing prospectus that we may authorize for use in connection with this offering completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

9

TABLE OF CONTENTS​

USE OF PROCEEDS

Except as described in any applicable prospectus supplement or in any free writing prospectuses we have authorized for use in connection with a specific offering, we currently intend to use the net proceeds from the sale of the securities offered by us hereunder, if any, for working capital, capital expenditures and general corporate purposes, which may include, among other things, funding research and development, clinical trials, vendor payables, potential regulatory submissions, hiring additional personnel and capital expenditures. We may also use a portion of the net proceeds to in-license, acquire, or invest in additional businesses, technologies, products, or assets, though we currently have no specific agreements, commitments, or understandings with respect to any in-licensing or acquisitions.

The amounts and timing of our use of the net proceeds from this offering will depend on a number of factors, such as the timing and progress of our research and development efforts, the timing and progress of any partnering and commercialization efforts, technological advances and the competitive environment for our products. As of the date of this prospectus, we cannot specify with certainty all of the particular uses for the net proceeds to us from the sale of the securities offered by us hereunder. Accordingly, our management will have broad discretion in the timing and application of these proceeds. Pending application of the net proceeds as described above, we intend to temporarily invest the proceeds in short-term, interest-bearing instruments.

10

TABLE OF CONTENTS​

DESCRIPTION OF CAPITAL STOCK

As of the date of this prospectus, our authorized capital stock consists of 60,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of preferred stock, par value $0.01 per share.

The following summary description of our capital stock is based on the provisions of our restated certificate of incorporation, or our Certificate of Incorporation, our second amended and restated bylaws, or our Bylaws, and the applicable provisions of the Delaware General Corporation Law, or DGCL. This information may not be complete in all respects and is qualified entirely by reference to the provisions of our Certificate of Incorporation, our Bylaws and the DGCL. For information on how to obtain copies of our Certificate of Incorporation and our Bylaws, see “Where You Can Find More Information.”

Common Stock

As of March 22, 2024, we had 21,584,256 shares of common stock outstanding, which amount gives effect to a 1-for-20 reverse stock split of our common stock effected on March 14, 2024 and a private placement of shares of our common stock and accompanying warrants to purchase common stock that closed on March 18, 2024.

Voting Rights

Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The affirmative vote of holders of 662∕3% of the voting power of all of the then-outstanding shares of capital stock, voting as a single class, will be required to amend certain provisions of our Certificate of Incorporation, including provisions relating to amending our Bylaws, the classified board, the size of our board, removal of directors, director liability, vacancies on our board, special meetings, stockholder notices, actions by written consent and exclusive jurisdiction.

Dividends

Subject to preferences that may apply to any outstanding preferred stock, holders of our common stock are entitled to receive ratably any dividends that our board of directors may declare out of funds legally available for that purpose on a non-cumulative basis.

Liquidation

In the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preference of any outstanding preferred stock.

Rights and Preferences

Holders of our common stock have no preemptive, conversion, subscription or other rights, and there are no redemption or sinking fund provisions applicable to our common stock. The rights, preferences and privileges of the holders of our common stock are subject to and may be adversely affected by the rights of the holders of shares of any series of our preferred stock that we may designate in the future.

Common Stock Equivalents

As of March 22, 2024, we had issued and outstanding 124 performance stock unit awards and 2,628,610 stock option awards under our equity incentive plans. At such date, we also had outstanding warrants to acquire an aggregate of 13,136,193 shares of our common stock, including the Private Placement Warrants (as defined below).

Private Placement Warrants

On March 18, 2024, in connection with a private placement, we issued warrants to purchase an aggregate of 12,857,133 shares of our common stock, or the Private Placement Warrants. The Private Placement Warrants have a per share exercise price equal to $7.70, subject to proportional adjustments in the event of stock splits or combinations or similar events. The Private Placement Warrants are exercisable only for cash, except in limited circumstances, at any time after the date of issuance, or the Issue Date, and will expire on March 18, 2029. A holder of Private Placement Warrants may not exercise the Private Placement Warrant if the holder, together with its affiliates, would beneficially own more than a specified percentage of the outstanding common stock (4.99%, 9.99% or 19.99%, as applicable), immediately after giving

11

TABLE OF CONTENTS

effect to such exercise, which may be increased or decreased at the holders’ option (not to exceed 19.99%), effective 61 days after written notice to us.

In addition, we may require the holders to cash exercise the Private Placement Warrants under certain circumstances as follows: (i) if the volume-weighted average price of our common stock equals or exceeds $20.00 per share (subject to adjustment in the event of stock splits, combinations or similar events) for 30 consecutive days, or the Stock Price Condition, at any time after we publicly announces topline data from our NORSE EIGHT clinical trial evidencing satisfaction of the trial’s primary endpoints, or the NORSE EIGHT Announcement, upon the consent of a majority of the members of our board of directors, we may require the holders to exercise up to 20% of the aggregate number of Private Placement Warrants issued to such holder on the Issue Date; and (ii) we may require up to the remainder of the Private Placement Warrants be exercised (A) if the Stock Price Condition is satisfied at any time after we publicly announce approval from the FDA of the BLA for ONS-5010, upon the consent of a majority of the members of our board of directors or (B) if the Stock Price Condition is satisfied at any time after the NORSE EIGHT Announcement, upon the unanimous consent of the members of our board of directors present at duly called meeting.

Preferred Stock

Our board of directors has the authority, without further action by our stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series and to fix the number, rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences and sinking fund terms, and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. The issuance of our preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control or other corporate action. Our board of directors has previously designated 1,000,000 shares as “Series A Convertible Preferred Stock,” 200,000 shares as “Series A-1 Convertible Preferred Stock” and 1,500,000 shares as “Series B Convertible Preferred Stock.” As of March 22, 2024, we did not have any shares of preferred stock issued and outstanding.

We will incorporate by reference as an exhibit to the registration statement, which includes this prospectus, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering. This description and the applicable prospectus supplement will include:

•

the title and stated value;

​

•

the number of shares authorized;

​

•

the liquidation preference per share;

​

•

the purchase price;

​

•

the dividend rate, period and payment date, and method of calculation for dividends;

​

•

whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

​

•

the procedures for any auction and remarketing, if any;

​

•

the provisions for a sinking fund, if any;

​

•

the provisions for redemption or repurchase, if applicable, and any restrictions on our ability to exercise those redemption and repurchase rights;

​

•

any listing of the preferred stock on any securities exchange or market;

​

•

whether the preferred stock will be convertible into our common stock, and, if applicable, the conversion price, or how it will be calculated, and the conversion period;

​

•

whether the preferred stock will be exchangeable into debt securities, and, if applicable, the exchange price, or how it will be calculated, and the exchange period;

​

•

voting rights, if any, of the preferred stock;

​

12

TABLE OF CONTENTS

•

preemptive rights, if any;

​

•

restrictions on transfer, sale or other assignment, if any;

​

•

whether interests in the preferred stock will be represented by depositary shares;

​

•

a discussion of any material U.S. federal income tax considerations applicable to the preferred stock;

​

•

the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs;

​

•

any limitations on issuance of any class or series of preferred stock ranking senior to or on a parity with the series of preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs; and

​

•

any other specific terms, preferences, rights or limitations of, or restrictions on, the preferred stock.

​

When we issue shares of preferred stock under this prospectus, the shares will fully be paid and nonassessable and will not have, or be subject to, any preemptive or similar rights.

Stockholder Registration Rights

Certain holders of our securities, including certain holders of 5% of our capital stock, and certain of our directors are entitled to certain rights with respect to registration of such securities under the Securities Act. These securities are referred to as registrable securities. The holders of these registrable securities possess registration rights pursuant to the terms of registration rights agreements.

In general, the registration of shares of our common stock pursuant to the exercise of registration rights enables the holders to trade such shares without restriction under the Securities Act when the applicable registration statement is declared effective. We generally have agreed to pay the registration expenses for such registration statements, other than underwriting discounts, selling commissions and stock transfer taxes, of the shares registered.

Generally, in an underwritten offering, the managing underwriter, if any, has the right, subject to specified conditions, to limit the number of shares the holders may include. We must use commercially reasonable efforts to keep the registration statement effective until the earlier of the date on which all registrable securities covered by such registration statement have been sold, or at such time that the holders of the registrable securities can sell their shares under Rule 144 of the Securities Act during any three-month period.

Anti-Takeover Provisions of Delaware Law and Our Charter Documents

Section 203 of the DGCL

We are subject to Section 203 of the DGCL, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:

•

before such date, the board of directors of the corporation approved either the business combination or the transaction that resulted in the stockholder becoming an interested stockholder;

​

•

upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction began, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the interested stockholder) those shares owned (1) by persons who are directors and also officers and (2) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; and

​

•

on or after such date, the business combination is approved by the board of directors and authorized at an annual or special meeting of the stockholders, and not by written consent, by the affirmative vote of at least 662∕3% of the outstanding voting stock that is not owned by the interested stockholder.

​

13

TABLE OF CONTENTS

In general, Section 203 defines a “business combination” to include the following:

•

any merger or consolidation involving the corporation and the interested stockholder;

​

•

any sale, transfer, pledge or other disposition of 10% or more of the assets of the corporation involving the interested stockholder;

​

•

subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder;

​

•

any transaction involving the corporation that has the effect of increasing the proportionate share of the stock or any class or series of the corporation beneficially owned by the interested stockholder;

​

•

the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits by or through the corporation; and

​

•

in general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.

​

The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to acquire us even though such a transaction may offer our stockholders the opportunity to sell their stock at a price above the prevailing market price.

Certificate of Incorporation and Bylaws

Among other things, our Certificate of Incorporation and Bylaws:

•

permit our board of directors to issue up to 10,000,000 shares of preferred stock, with any rights, preferences and privileges as they may designate, including the right to approve an acquisition or other change in control;

​

•

provide that the authorized number of directors may be changed only by resolution of our board of directors;

​

•

provide that our board of directors is classified into three classes of directors;

​

•

provide that, subject to the rights of any series of preferred stock to elect directors, directors may only be removed for cause, which removal may be effected, subject to any limitation imposed by law, by the holders of at least a majority of the voting power of all of our then-outstanding shares of the capital stock entitled to vote generally at an election of directors;

​

•

provide that all vacancies, including newly created directorships, may, except as otherwise required by law, be filled by the affirmative vote of a majority of directors then in office, even if less than a quorum;

​

•

require that any action to be taken by our stockholders must be effected at a duly called annual or special meeting of stockholders and not be taken by written consent or electronic transmission;

​

•

provide that stockholders seeking to present proposals before a meeting of stockholders or to nominate candidates for election as directors at a meeting of stockholders must provide advance notice in writing, and also specify requirements as to the form and content of a stockholder’s notice;

​

•

provide that special meetings of our stockholders may be called only by the chairman of our board of directors, our chief executive officer or president or by our board of directors pursuant to a resolution adopted by a majority of the total number of authorized directors; and

​

•

not provide for cumulative voting rights, therefore allowing the holders of a majority of the shares of common stock entitled to vote in any election of directors to elect all of the directors standing for election, if they should so choose.

​

The amendment of any of these provisions requires approval by the holders of at least 662∕3% of the voting power of all of our then-outstanding common stock entitled to vote generally in the election of directors, voting together as a single class.

14

TABLE OF CONTENTS

The combination of these provisions may make it more difficult for our existing stockholders to replace our board of directors as well as for another party to obtain control of us by replacing our board of directors. Because our board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change our control.

These provisions are intended to enhance the likelihood of continued stability in the composition of our board of directors and its policies and to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to reduce our vulnerability to hostile takeovers and to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of delaying changes in our control or management. As a consequence, these provisions may also inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts. We believe that the benefits of these provisions, including increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our company, outweigh the disadvantages of discouraging takeover proposals, because negotiation of takeover proposals could result in an improvement of their terms.

Choice of Forum

Our Certificate of Incorporation and our Bylaws provide that the Court of Chancery of the State of Delaware is the sole and exclusive forum for any derivative action or proceeding brought on our behalf; any action asserting a breach of fiduciary duty to us or our stockholders; any action asserting a claim against us arising pursuant to any provision of the DGCL, our Certificate of Incorporation or our Bylaws; or any action asserting a claim against us that is governed by the internal affairs doctrine.

These exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees and may discourage these types of lawsuits. Furthermore, the enforceability of similar choice of forum provisions in other companies’ certificates of incorporation has been challenged in legal proceedings, and it is possible that, in connection with one or more actions or proceedings described above, a court could find the choice of forum provisions contained in our Certificate of Incorporation to be inapplicable or unenforceable.

Listing

Our common stock is listed on The Nasdaq Capital Market under the trading symbol “OTLK”. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on The Nasdaq Capital Market or any securities market or other exchange of the preferred stock or other securities covered by such prospectus supplement.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Equinti Trust Company, LLC. Its address is 48 Wall Street, Floor 23, New York, NY 10005.

15

TABLE OF CONTENTS​

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue the debt securities under the indenture that we will enter into with the trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.

General

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.

We may issue the debt securities issued under the indenture as “discount securities,” which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with “original issue discount,” or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.

We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

•

the title of the series of debt securities;

​

•

any limit upon the aggregate principal amount that may be issued;

​

•

the maturity date or dates;

​

•

the form of the debt securities of the series;

​

•

the applicability of any guarantees;

​

•

whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

​

•

whether the debt securities rank as senior debt, senior subordinated debt, subordinated debt or any combination thereof, and the terms of any subordination;

​

•

if the price (expressed as a percentage of the aggregate principal amount thereof) at which such debt securities will be issued is a price other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof, or if applicable, the portion of the principal amount of such debt securities that is convertible into another security or the method by which any such portion shall be determined;

​

16

TABLE OF CONTENTS

•

the interest rate or rates, which may be fixed or variable, or the method for determining the rate or rates and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;

​

•

our right, if any, to defer payment of interest and the maximum length of any such deferral period;

​

•

if applicable, the date or dates after which, or the period or periods during which, and the price or prices at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemption provisions;

​

•

the date or dates, if any, on which, and the price or prices at which we are obligated, pursuant to any mandatory sinking fund or analogous fund provisions or otherwise, to redeem, or at the holder’s option to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;

​

•

the denominations in which we will issue the series of debt securities, if other than denominations of  $1,000 and any integral multiple thereof;

​

•

any and all terms, if applicable, relating to any auction or remarketing of the debt securities of that series and any security for our obligations with respect to such debt securities and any other terms which may be advisable in connection with the marketing of debt securities of that series;

​

•

whether the debt securities of the series shall be issued in whole or in part in the form of a global security or securities, the terms and conditions, if any, upon which such global security or securities may be exchanged in whole or in part for other individual securities, and the depositary for such global security or securities;

​

•

if applicable, the provisions relating to conversion or exchange of any debt securities of the series and the terms and conditions upon which such debt securities will be so convertible or exchangeable, including the conversion or exchange price, as applicable, or how it will be calculated and may be adjusted, any mandatory or optional (at our option or the holders’ option) conversion or exchange features, the applicable conversion or exchange period and the manner of settlement for any conversion or exchange;

​

•

if other than the full principal amount thereof, the portion of the principal amount of debt securities of the series which shall be payable upon declaration of acceleration of the maturity thereof;

​

•

additions to or changes in the covenants applicable to the particular debt securities being issued, including, among others, the consolidation, merger or sale covenant;

​

•

additions to or changes in the events of default with respect to the securities and any change in the right of the trustee or the holders to declare the principal, premium, if any, and interest, if any, with respect to such securities to be due and payable;

​

•

additions to or changes in or deletions of the provisions relating to covenant defeasance and legal defeasance;

​

•

additions to or changes in the provisions relating to satisfaction and discharge of the indenture;

​

•

additions to or changes in the provisions relating to the modification of the indenture both with and without the consent of holders of debt securities issued under the indenture;

​

•

the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S. dollars;

​

•

whether interest will be payable in cash or additional debt securities at our or the holders’ option and the terms and conditions upon which the election may be made;

​

•

the terms and conditions, if any, upon which we will pay amounts in addition to the stated interest, premium, if any and principal amounts of the debt securities of the series to any holder that is not a “United States person” for federal tax purposes;

​

•

any restrictions on transfer, sale or assignment of the debt securities of the series; and

​

17

TABLE OF CONTENTS

•

any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, any other additions or changes in the provisions of the indenture, and any terms that may be required by us or advisable under applicable laws or regulations.

​

Conversion or Exchange Rights

We will set forth in the applicable prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of our assets as an entirety or substantially as an entirety. However, any successor to or acquirer of such assets (other than a subsidiary of ours) must assume all of our obligations under the indenture or the debt securities, as appropriate.

Events of Default under the Indenture

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:

•

if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and payable, and such default continues for a period of 90 days; provided, however, that a valid extension of an interest payment period by us in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of interest for this purpose;

​

•

if we fail to pay the principal of, or premium, if any, on any series of debt securities as and when the same shall become due and payable whether at maturity, upon redemption, by declaration or otherwise, or in any payment required by any sinking or analogous fund established with respect to such series; provided, however, that a valid extension of the maturity of such debt securities in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of principal or premium, if any;

​

•

if we fail to observe or perform any other covenant or agreement contained in the debt securities or the indenture, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive written notice of such failure, requiring the same to be remedied and stating that such is a notice of default thereunder, from the trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and

​

•

if specified events of bankruptcy, insolvency or reorganization occur.

​

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

18

TABLE OF CONTENTS

Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

•

the direction so given by the holder is not in conflict with any law or the applicable indenture; and

​

•

subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

​

A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:

•

the holder has given written notice to the trustee of a continuing event of default with respect to that series;

​

•

the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request;

​

•

such holders have offered to the trustee indemnity satisfactory to it against the costs, expenses and liabilities to be incurred by the trustee in compliance with the request; and

​

•

the trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.

​

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.

Modification of Indenture; Waiver

We and the trustee may change an indenture without the consent of any holders with respect to specific matters:

•

to cure any ambiguity, defect or inconsistency in the indenture or in the debt securities of any series;

​

•

to comply with the provisions described above under “Description of Debt Securities—​Consolidation, Merger or Sale;”

​

•

to provide for uncertificated debt securities in addition to or in place of certificated debt securities;

​

•

to add to our covenants, restrictions, conditions or provisions such new covenants, restrictions, conditions or provisions for the benefit of the holders of all or any series of debt securities, to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred upon us in the indenture;

​

•

to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue, authentication and delivery of debt securities, as set forth in the indenture;

​

•

to make any change that does not adversely affect the interests of any holder of debt securities of any series in any material respect;

​

•

to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided above under “Description of Debt Securities—General” to

​

19

TABLE OF CONTENTS

establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;

•

to evidence and provide for the acceptance of appointment under any indenture by a successor trustee; or

​

•

to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act.

​

In addition, under the indenture, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may make the following changes only with the consent of each holder of any outstanding debt securities affected:

•

extending the fixed maturity of any debt securities of any series;

​

•

reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any series of any debt securities; or

​

•

reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver.

​

Discharge

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

•

provide for payment;

​

•

register the transfer or exchange of debt securities of the series;

​

•

replace stolen, lost or mutilated debt securities of the series;

​

•

pay principal of and premium and interest on any debt securities of the series;

​

•

maintain paying agencies;

​

•

hold monies for payment in trust;

​

•

recover excess money held by the trustee;

​

•

compensate and indemnify the trustee; and

​

•

appoint any successor trustee.

​

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of  $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in the applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

20

TABLE OF CONTENTS

Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional security registrars or transfer agents or rescind the designation of any security registrars or transfer agent or approve a change in the office through which any security registrars or transfer agent acts, except that we will be required to maintain a security registrar and a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

•

issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or

​

•

register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

​

Information Concerning the Trustee

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We may at any time rescind the designation or any paying agent or approve a change in the office through which any paying agent acts, except that we will be required to maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

21

TABLE OF CONTENTS​

DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may consist of warrants to purchase common stock, preferred stock or debt securities and may be issued in one or more series. Warrants may be issued independently or together with common stock, preferred stock or debt securities offered by any prospectus supplement and may be attached to or separate from those securities. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement and any applicable free writing prospectus. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We have filed forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants being offered as exhibits to the registration statement of which this prospectus is a part. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant agreement, if any, including a form of warrant certificate, that describes the terms of the particular series of warrants we are offering. The following summaries of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to the particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplements related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete warrant agreements and warrant certificates that contain the terms of the warrants.

General

We will describe in the applicable prospectus supplement the terms of the series of warrants being offered, including, to the extent applicable:

•

the offering price and aggregate number of warrants offered;

​

•

the currency for which the warrants may be purchased;

​

•

the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;

​

•

in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at, and currency in which, this principal amount of debt securities may be purchased upon such exercise;

​

•

in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;

​

•

the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;

​

•

the terms of any rights to redeem or call the warrants;

​

•

any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;

​

•

the dates on which the right to exercise the warrants will commence and expire;

​

•

the manner in which the warrant agreements and warrants may be modified;

​

•

a discussion of material or special U.S. federal income tax considerations of holding or exercising the warrants;

​

•

the terms of the securities issuable upon exercise of the warrants; and

​

•

any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

​

22

TABLE OF CONTENTS

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

•

in the case of warrants to purchase common stock or preferred stock, the right to receive dividends, if any, or, payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any; or

​

•

in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture.

​

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent in connection with the exercise of the warrant.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Governing Law

Unless we provide otherwise in the applicable prospectus supplement, the warrants and warrant agreements, and any claim, controversy or dispute arising under or related to the warrants or warrant agreements, will be governed by and construed in accordance with the laws of the State of New York.

Enforceability of Rights by Holders of Warrants

Each warrant agent, if any, will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

23

TABLE OF CONTENTS​

LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depositary or warrant agent maintain for this purpose as the “holders” of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as “indirect holders” of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a global security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in “street name.” Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any such trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not legal holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee or any third party employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the legal holder, we have no further responsibility for the payment or notice even if that legal holder is required, under agreements with its participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture, or for other purposes. In such

24

TABLE OF CONTENTS

an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

Special Considerations for Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

•

how it handles securities payments and notices;

​

•

whether it imposes fees or charges;

​

•

how it would handle a request for the holders’ consent, if ever required;

​

•

whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted in the future;

​

•

how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to protect their interests; and

​

•

if the securities are in book-entry form, how the depositary’s rules and procedures will affect these matters.

​

Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under the section titled “Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

Special Considerations for Global Securities

The rights of an indirect holder relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only in the form of a global security, an investor should be aware of the following:

•

an investor cannot cause the securities to be registered in his or her name, and cannot obtain non-global certificates for his or her interest in the securities, except in the special situations we describe below;

​

•

an investor will be an indirect holder and must look to his or her own bank or broker for payments on the securities and protection of his or her legal rights relating to the securities, as we describe above;

​

25

TABLE OF CONTENTS

•

an investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required by law to own their securities in non-book-entry form;

​

•

an investor may not be able to pledge his or her interest in a global security in circumstances where certificates representing the securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective;

​

•

the depositary’s policies, which may change from time to time, will govern payments, transfers, exchanges and other matters relating to an investor’s interest in a global security;

​

•

we and any applicable trustee have no responsibility for any aspect of the depositary’s actions or for its records of ownership interests in a global security, nor do we or any applicable trustee supervise the depositary in any way;

​

•

the depositary may, and we understand that DTC will, require that those who purchase and sell interests in a global security within its book-entry system use immediately available funds, and your bank or broker may require you to do so as well; and

​

•

financial institutions that participate in the depositary’s book-entry system, and through which an investor holds its interest in a global security, may also have their own policies affecting payments, transfers, exchanges, notices and other matters relating to the securities.

​

There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

Special Situations When a Global Security Will Be Terminated

In a few special situations described below, a global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

Unless we provide otherwise in the applicable prospectus supplement, a global security will terminate when the following special situations occur:

•

if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security and we do not appoint another institution to act as depositary within 90 days;

​

•

if we notify any applicable trustee that we wish to terminate that global security; or

​

•

if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.

​

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the applicable prospectus supplement. When a global security terminates, the depositary, and neither we nor any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

26

TABLE OF CONTENTS​

PLAN OF DISTRIBUTION

We may sell the securities covered hereby from time to time pursuant to underwritten public offerings, direct sales to the public, negotiated transactions, block trades or a combination of these methods. A distribution of these securities offered by this prospectus may also be effected through the issuance of derivative securities, including, without limitation, warrants. We may sell the securities to or through underwriters or dealers, through agents, or directly to one or more purchasers. We may distribute securities from time to time in one or more transactions:

•

at a fixed price or prices, which may be changed;

​

•

at market prices prevailing at the time of sale;

​

•

at prices related to such prevailing market prices; or

​

•

at negotiated prices.

​

We may also sell equity securities covered by this registration statement in an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act. Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price, either:

•

on or through the facilities of The Nasdaq Capital Market or any other securities exchange or quotation or trading service on which such securities may be listed, quoted or traded at the time of sale; and/or

​

•

to or through a market maker other than on The Nasdaq Capital Market or such other securities exchanges or quotation or trading services.

​

Such at-the-market offerings, if any, may be conducted by underwriters acting as principal or agent.

A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including, to the extent applicable:

•

the name or names of any underwriters, dealers or agents, if any;

​

•

the purchase price of the securities and the proceeds we will receive from the sale;

​

•

any options pursuant to which underwriters may purchase additional securities from us;

​

•

any agency fees or underwriting discounts and other items constituting agents’ or underwriters’ compensation;

​

•

any public offering price;

​

•

any discounts or concessions allowed or reallowed or paid to dealers; and

​

•

any securities exchange or market on which the securities may be listed.

​

Only underwriters named in the prospectus supplement will be underwriters of the securities offered by the prospectus supplement.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement, other than securities covered by any option to purchase additional securities. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, the nature of any such relationship.

We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities, and we will describe any commissions and other

27

TABLE OF CONTENTS

compensation we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents and underwriters with indemnification against civil liabilities related to this offering, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

All securities we may offer, other than common stock, will be new issues of securities with no established trading market. Any agents or underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities. There is currently no market for any of the offered securities, other than our common stock which is listed on The Nasdaq Capital Market. We have no current plans for listing of the preferred stock, debt securities or warrants on any securities exchange or quotation system; any such listing with respect to any particular preferred stock, debt securities or warrants will be described in the applicable prospectus supplement or other offering materials, as the case may be.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Rule 103 of Regulation M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time. These transactions may be effected on any exchange or over-the-counter market or otherwise.

Any agents and underwriters who are qualified market makers on The Nasdaq Capital Market may engage in passive market making transactions in the securities on The Nasdaq Capital Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

28

TABLE OF CONTENTS​​​

LEGAL MATTERS

Unless otherwise indicated in the applicable prospectus supplement, certain legal matters in connection with the offering and the validity of the securities offered by this prospectus, and any prospectus supplement thereto, will be passed upon by Cooley LLP, Chicago, Illinois. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of Outlook Therapeutics, Inc. as of September 30, 2023 and 2022, and for the years then ended, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the September 30, 2023 consolidated financial statements contains an explanatory paragraph that states that the Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit, that raise substantial doubt about its ability to continue as a going concern. The consolidated financial statements do not include any adjustments that might result from the outcome of that uncertainty.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement we filed with the SEC. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on information contained in this prospectus or incorporated by reference into this prospectus. We have not authorized any person to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered by this prospectus.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public at the SEC’s website at http://www.sec.gov.

We maintain a website at http://www.outlooktherapeutics.com. Information contained in or accessible through our website does not constitute a part of this prospectus.

29

TABLE OF CONTENTS​

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to incorporate by reference the information we file with it, which means that we can disclose important information to you by referring you to another document that we have filed separately with the SEC. You should read the information incorporated by reference because it is an important part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus. We incorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information and documents listed below that we have filed with the SEC (Commission File No. 001-37759):

•

our Annual Report on Form 10-K for the fiscal year ended September 30, 2023, filed with the SEC on December 22, 2023, or the 2023 Form 10-K, and amended on January 24, 2024;

​

•

our Quarterly Report on Form 10-Q for the quarter ended December 31, 2023 filed with the SEC on February 14, 2024;

​

•

our Current Reports on Form 8-K, filed with the SEC on October 20, 2023, November 2, 2023, December 6, 2023, January 24, 2024, March 7, 2024, March 18, 2024 and March 26, 2024, to the extent the information in such reports is filed and not furnished; and

​

•

the description of our common stock set forth in our registration statement on Form 8-A, filed with the SEC on April 29, 2016, as amended on May 11, 2016, including any further amendments thereto or reports filed for the purposes of updating this description, including Exhibit 4.1 of the 2023 Form 10-K.

​

We also incorporate by reference any future filings (other than Current Reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items unless such Form 8-K expressly provides to the contrary) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (i) after the date of the filing of the registration statement of which this prospectus is a part and prior to effectiveness of the registration statement and (ii) after the effectiveness of the registration statement of which this prospectus is a part but prior to the termination of all offerings of securities covered by this prospectus (Commission File No. 001-37759). Information in such future filings updates and supplements the information provided in this prospectus. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

We will furnish without charge to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request, a copy of any or all of the documents incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to Outlook Therapeutics, Inc., Attention: Corporate Secretary, 485 Route 1 South, Building F, Suite 320, Iselin, New Jersey 08830. Our phone number is (609) 619-3990. You may also view the documents that we file with the SEC and incorporate by reference in this prospectus on our corporate website at www.outlooktherapeutics.com. The information on our website is not incorporated by reference and is not a part of this prospectus.

30

TABLE OF CONTENTS

55,555,556 Shares of Common Stock

Warrants to Purchase 55,555,556 Shares of Common Stock

PROSPECTUS SUPPLEMENT

Joint Bookrunning Managers

​ Piper Sandler ​ ​ BTIG ​

Lead Manager

Brookline Capital Markets,

a division of Arcadia Securities, LLC

August 12, 2026