Sermonix takes 36.9% LeonaBio stake via warrants

Rhea-AI Filing Summary

LeonaBio, Inc. (LONA) is the subject of a Schedule 13D reporting that Sermonix Pharmaceuticals, Inc. and its CEO, David Portman, beneficially own 5,502,402 shares of LeonaBio common stock, or 36.9% of the class on an as-converted basis, through prefunded warrants received in a strategic collaboration.

The warrants were issued as partial consideration under a Securities Purchase Agreement and a License Agreement granting LeonaBio an exclusive license to develop and commercialize lasofoxifene, in exchange for royalties, milestones and the prefunded warrants. On August 24, 2026, Sermonix became eligible to exercise the prefunded warrants for 5,502,402 shares, subject to transactions effective October 26, 2026, including an assignment of 2,352,932 warrant shares to Perceptive Xontogeny, planned exercises for 3,149,470 shares, distributions-in-kind totaling 4,725,754 shares, and an assignment of 170,940 shares to a creditor.

Filing Explained

The filing separately discloses that David Portman received options for 350,000 LeonaBio shares in April 2026 for consulting services, with vesting scheduled to begin in April 2027; no exercise or issuance is reported here.

Key Figures

Beneficially owned shares: 5,502,402 shares of Common Stock Percent of class beneficially owned: 36.9 % Shares of Common Stock outstanding: 9,421,663 shares +5 more

8 metrics

Beneficially owned shares 5,502,402 shares of Common Stock Shares beneficially owned by Sermonix Pharmaceuticals, Inc. and David Portman on an as-converted basis

Percent of class beneficially owned 36.9 % Portion of LeonaBio common stock represented by 5,502,402 shares on an as-converted basis

Shares of Common Stock outstanding 9,421,663 shares LeonaBio common stock outstanding as disclosed in the Form 10-Q filed August 14, 2026

Prefunded warrants eligible to be exercised 5,502,402 shares Prefunded warrants held by Sermonix that became eligible for exercise on August 24, 2026

Warrants assigned to Perceptive Xontogeny 2,352,932 shares Portion of prefunded warrants to be assigned as a distribution-in-kind, effective October 26, 2026

Shares subject to warrant exercise 3,149,470 shares Shares underlying warrants for which Sermonix took action to exercise, effective October 26, 2026

Distribution-in-kind of Common Stock 4,725,754 shares Shares of Common Stock declared as a distribution-in-kind, including those assigned to Perceptive Xontogeny Venture Fund II, LP

Shares assigned to creditor 170,940 shares Common Stock to be remitted to a creditor in satisfaction of amounts owed

Key Terms

prefunded warrants, distribution-in-kind, Registration Rights Agreement, License Agreement, +1 more

5 terms

prefunded warrants financial

"Prefunded warrants to purchase shares of Common Stock of Issuer received by Sermonix"

Prefunded warrants are a security that gives the holder the right to convert the warrant into a share after paying a very small remaining amount because almost the full purchase price was paid upfront. They matter to investors because exercising them increases the company’s outstanding shares (dilution) and can provide immediate cash to the issuer while allowing holders to bypass ownership limits or simplify timing, similar to buying a nearly-complete gift card that only needs a tiny top-up to use.

distribution-in-kind financial

"Sermonix declared a distribution-in-kind with respect to 4,725,754 shares of Common Stock"

A distribution-in-kind is when a company or fund pays shareholders with assets—such as stock, bonds, or physical property—instead of cash. For investors it matters because the received items may be harder to sell, have different tax consequences, and can change the risk and value of their holdings, similar to being handed a slice of pie instead of money for your share of the bakery.

Registration Rights Agreement regulatory

"a Registration Rights Agreement, wherein the issuer agreed to prepare and file a registration statement"

A registration rights agreement is a contract that gives investors the option to have their ownership stakes officially registered with the government, making it easier to sell their shares later. This agreement matters because it provides investors with a clearer path to cash out their investments if they choose, offering more liquidity and confidence in their ability to sell their holdings when desired.

License Agreement regulatory

"a License Agreement, pursuant to which Sermonix granted the issuer an exclusive license"

A license agreement is a contract where the owner of intellectual property, technology, a brand, or other rights gives another party permission to use those assets under specified conditions, usually for fees, royalties or other payments. For investors it matters because such deals create or limit predictable revenue streams, affect profit margins, transfer legal and commercial risk, and can determine how quickly a company can grow — like renting out a patented tool to earn steady income while keeping ownership.

beneficially owned financial

"Aggregate amount beneficially owned by each reporting person 5,502,402.00"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

FAQ

What percentage of LeonaBio (LONA) does Sermonix Pharmaceuticals report beneficially owning?

Sermonix Pharmaceuticals and David Portman report beneficial ownership of 5,502,402 shares of LeonaBio common stock, representing 36.9% of the class, based on 9,421,663 shares outstanding and assuming exercise of their prefunded warrants.

How did Sermonix acquire its LeonaBio (LONA) position?

Sermonix received prefunded warrants to purchase LeonaBio common stock as partial consideration for licensing intellectual property under a License Agreement and a Securities Purchase Agreement, forming part of a strategic collaboration around lasofoxifene.

What key warrant-related transactions involving LONA are described for October 26, 2026?

Effective October 26, 2026, Sermonix plans an assignment of prefunded warrants for 2,352,932 shares to Perceptive Xontogeny, exercise of warrants for 3,149,470 shares, a distribution-in-kind of 4,725,754 shares, and assignment of 170,940 shares to a creditor.

What is the size of LeonaBio’s (LONA) share base used in the 13D calculations?

The reported ownership percentages use an aggregate of 9,421,663 shares of LeonaBio common stock outstanding, as disclosed in LeonaBio’s Form 10-Q filed on August 14, 2026, and give effect to the exercise of warrants held by the reporting persons.

What consulting-related equity did David Portman receive from LeonaBio (LONA)?

In April 2026, David Portman was granted options to purchase 350,000 shares of LeonaBio common stock as consideration for consulting services, subject to a vesting schedule commencing in April 2027.

What agreements govern the relationship between LeonaBio (LONA) and Sermonix?

LeonaBio and Sermonix entered into a Securities Purchase Agreement, a Registration Rights Agreement covering resale of shares, and a License Agreement granting LeonaBio an exclusive license to develop and commercialize lasofoxifene, except in certain Asian territories.

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

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Available on EDGAR 08/31/2026 - 04:32 PM Accepted by SEC EDGAR 08/31/2026 - 04:31 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

LeonaBio, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

04746L203

(CUSIP Number)

David Portman
250 E Broad St, Ste 250
Columbus, OH, 43215
614-582-6849

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/24/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 04746L203

1

Name of reporting person

Sermonix Pharmaceuticals, Inc.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 5,502,402.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 5,502,402.00

11

Aggregate amount beneficially owned by each reporting person

5,502,402.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

36.9 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP Number(s): 04746L203

1

Name of reporting person

Portman David J.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 5,502,402.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 5,502,402.00

11

Aggregate amount beneficially owned by each reporting person

5,502,402.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

36.9 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock
(b)	Name of Issuer: LeonaBio, Inc.
(c)	Address of Issuer's Principal Executive Offices: 18706 NORTH CREEK PARKWAY, SUITE 104, BOTHELL, WASHINGTON , 98011.
Item 2.	Identity and Background
(a)	This Schedule 13D is being filed by Sermonix Pharmaceuticals, Inc., a Delaware corporation, and David Portman, its CEO (each a Reporting Person). The agreement among the Reporting Persons to file this Schedule 13D jointly in accordance with Rule 13d-1(k) of the Securities Exchange Act of 1934, as amended, is attached as Exhibit 7 hereto.
(b)	250 E. Broad St., Suite 250 Columbus, OH 43215
(c)	The principal business of Sermonix Pharmaceuticals, Inc. is pharmaceutical intellectual property licensing and clinical development. The principal occupation of David Portman is the CEO of Sermonix Pharmaceuticals.
(d)	The Reporting Persons have not, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).
(e)	The Reporting Persons have not, within the last five years, been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	David Portman is a citizen of the United States.
Item 3.	Source and Amount of Funds or Other Consideration
	Prefunded warrants to purchase shares of Common Stock of Issuer received by Sermonix Pharmaceuticals, Inc. were partial consideration for the licensing of intellectual property held by Sermonix Pharmaceuticals, Inc. to the Issuer pursuant to a License Agreement.
Item 4.	Purpose of Transaction
	The acquisition of securities of the issuer is part of a strategic collaboration as previously disclosed between Sermonix Pharmaceuticals, Inc. and the Issuer, as set forth in the previously disclosed License Agreement and Securities Purchase Agreement.
Item 5.	Interest in Securities of the Issuer
(a)	The information set forth in rows 11 and 13 of the cover pages to this Schedule 13D is incorporated by reference. The percentages set forth in row 13 are based on an aggregate of 9,421,663 shares of Common Stock outstanding, as disclosed by the Issuer in its Quarterly Report on Form 10-Q filed with the SEC on August 14, 2026, and give effect to the exercise of warrants held by the Reporting Persons for an aggregate of 5,502,402 shares of Common Stock.
(b)	The information set forth in rows 7 through 10 of the cover pages to this Schedule 13D is incorporated by reference.
(c)	On August 24, 2026, Sermonix Pharmaceuticals, Inc. became eligible to exercise its prefunded warrants to purchase 5,502,402 shares of Common Stock in the Issuer, pursuant to the transactions contemplated by the License Agreement and Securities Purchase Agreement. The warrant was previously subject to an exercise cap equal to 4.99% of outstanding Issuer common stock (which cap applied to Sermonix Pharmaceuticals and any affiliates on an aggregate basis). In addition to the foregoing, Sermonix Pharmaceuticals effected an assignment to transfer a portion of its prefunded warrants to purchase 2,352,932 shares of Common Stock in the Issuer to Perceptive Xontogeny as a distribution-in-kind, which assignment will be effective October 26, 2026. Sermonix took action to exercise the warrant with respect to 3,149,470 shares of Common Stock, effective October 26, 2026. Sermonix declared a distribution-in-kind with respect to 4,725,754 shares of Common Stock (including the 2,352,932 assigned to Perceptive Xonotogeny Venture Fund II, LP), payable on October 26, 2026. Sermonix also entered into an agreement with a creditor to assign 170,940 to such creditor in satisfaction of amounts owed, with such remittance of Common Stock to occur on or shortly after October 26, 2026. Except for the transactions described in this Item 5(c), the Reporting Person has not effected any transaction in shares of Common Stock during the past 60 days.
(d)	Shareholders of Sermonix Pharmaceuticals, Inc. who will have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, more than 5 percent of the Common Stock in the Issuer are: Perceptive Xontogeny Venture Fund II, LP; HPW Asset Management Limited
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	On December 18, 2025, the issuer entered into two agreements with Sermonix Pharmaceuticals, Inc.: 1) the Securities Purchase Agreement to purchase the prefunded warrant to purchase Common Stock reported on this Schedule 13D, 3) a Registration Rights Agreement, wherein the issuer agreed to prepare and file a registration statement to register the resale of the shares of Common Stock purchased pursuant to the Securities Purchase Agreement, and 3) a License Agreement, pursuant to which Sermonix granted the issuer an exclusive license to develop, manufacture and commercialize lasofoxifene on a worldwide basis except with respect to certain territories in Asia, in exchange for royalties, milestone payments, and the prefunded warrant to purchase common stock in the issuer. On December 23, 2025, the transactions contemplated by these agreements were closed. On August 24, 2026, Sermonix Pharmaceuticals effected an assignment to transfer a portion of its prefunded warrants to purchase 2,352,932 shares of Common Stock in the Issuer to Perceptive Xontogeny as a distribution-in-kind, which assignment will be effective October 26, 2026. On August 24, 2026, Sermonix took action to exercise the warrant with respect to 3,149,470 shares of Common Stock, effective October 26, 2026. Sermonix declared a distribution-in-kind with respect to 4,725,754 shares of Common Stock (including the 2,352,932 assigned to Perceptive Xonotogeny Venture Fund II, LP), payable on October 26, 2026. Sermonix also entered into an agreement with a creditor to assign 170,940 to such creditor in satisfaction of amounts owed, with such remittance of Common Stock to occur on or shortly after October 26, 2026. David Portman was granted, in April 2026, options to purchase 350,000 shares of Common Stock in the Issuer in exchange for consulting services, subject to a vesting schedule commencing in April of 2027. The foregoing descriptions do not purport to be complete and are qualified in their entirety by reference to the full text of the agreements, incorporated by reference as exhibits hereto.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 7 Joint Filing Agreement (filed herewith) Exhibit 8 Securities Purchase Agreement (incorporated by reference to Exhibit 10.31 to the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 31, 2026) Exhibit 9 Registration Rights Agreement (incorporated by reference to Exhibit 4.8 to the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 31, 2026) Exhibit 10 License Agreement (incorporated by reference to Exhibit 10.28 to the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 31, 2026) Exhibit 24.1 Sermonix Pharmaceuticals Power of Attorney (filed herewith) Exhibit 24.2 David Portman Power of Attorney (filed herewith)

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Sermonix Pharmaceuticals, Inc.

Signature:	/s/ David Portman
Name/Title:	David Portman, Chief Executive Officer
Date:	08/31/2026

Portman David J.

Signature:	/s/ David Portman
Name/Title:	David Portman
Date:	08/31/2026