Boundless Bio adds $0.00001 warrants in Serapha merger

Rhea-AI Filing Summary

Boundless Bio, Inc. (BOLD) reports that on August 28, 2026 it entered into Amendment No. 1 to its Agreement and Plan of Merger and Reorganization with Boulder Merger Sub Corp. and Serapha Bio, Inc. The amendment refines mechanics around the planned merger under which Serapha will become a wholly owned subsidiary of Boundless Bio.

The amendment clarifies definitions and provisions related to the planned Company Pre-Closing Financing, specifies that all outstanding Serapha restricted stock units will convert into Boundless Bio restricted stock units adjusted by the Exchange Ratio, and introduces pre-funded warrants with a $0.00001 per-share exercise price as merger consideration when issuing common stock would breach a holder’s Beneficial Ownership Limitation. It also lowers the voting standard for increasing authorized Boundless Bio common shares to a majority of shares properly cast, rather than a majority of shares outstanding and entitled to vote. All other merger terms remain as previously disclosed. The company highlights multiple risks that could affect completion and outcomes of the merger and related financing, including regulatory approvals, satisfaction of closing conditions, exchange ratio adjustments, market price movements, and potential non-consummation of the pre-closing financing.

8-K Event Classification

2 items: 1.01, 9.01

2 items

Item 1.01 Entry into a Material Definitive Agreement Business

The company signed a significant contract such as a merger agreement, credit facility, or major partnership.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, or exhibit attachments filed with this report.

Key Figures

Pre-funded warrant exercise price: $0.00001 per share

1 metrics

Pre-funded warrant exercise price $0.00001 per share Exercise price for pre-funded warrants issued as Merger Consideration

Key Terms

Exchange Ratio, pre-funded warrants, Beneficial Ownership Limitation, Company Pre-Closing Financing, +1 more

5 terms

Exchange Ratio financial

"number of shares subject to each such Assumed RSU adjusted by the Exchange Ratio"

The exchange ratio is the number used to decide how many shares of one company you get for each share you own in another company during a merger or acquisition. It’s like a recipe that tells you how to swap shares fairly, ensuring both companies’ values are balanced. This ratio matters because it determines how ownership divides between the companies' shareholders.

pre-funded warrants financial

"add mechanics for the issuance of pre-funded warrants (with an exercise price"

Pre-funded warrants are financial instruments that give investors the right to purchase a company's stock at a set price, but with most or all of the purchase price paid upfront. They function like a coupon or gift card for stock, allowing investors to buy shares later at a fixed price, which can be beneficial if they want to avoid future price increases. This makes them important for investors seeking flexibility and certainty in their investment plans.

Beneficial Ownership Limitation regulatory

"would cause a holder to exceed its applicable Beneficial Ownership Limitation"

A beneficial ownership limitation is a rule that caps the percentage of a company’s shares an investor can be treated as owning or controlling for voting, regulatory or tax purposes. It matters to investors because it can restrict how many shares a person or group can buy or vote, affect takeover chances, and influence share liquidity and value — like a speed limit that prevents any single driver from taking over the whole road.

Company Pre-Closing Financing financial

"including in relation to the Company Pre-Closing Financing"

Form S-4 regulatory

"Boundless Bio will file relevant materials with the SEC, including the Form S-4"

A Form S-4 is a legal document that companies file with the government to announce and explain a major business move, such as a merger or acquisition. It provides detailed information to help investors understand how the deal might affect the company's value and future prospects, similar to a detailed blueprint that clarifies the impact of a significant change.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Boundless Bio (BOLD) change in its merger agreement with Serapha Bio?

Boundless Bio entered Amendment No. 1 to the Merger Agreement, clarifying financing-related definitions, setting how Serapha RSUs convert into Boundless Bio RSUs using the Exchange Ratio, adding pre-funded warrant mechanics, and revising the voting standard for increasing authorized common shares.

How will Serapha Bio RSUs be treated in the Boundless Bio (BOLD) merger?

Each Serapha RSU outstanding immediately before the merger’s effective time will convert into an Assumed RSU covering shares of Boundless Bio common stock on generally the same terms, with the number of shares per award adjusted based on the Exchange Ratio.

What are the pre-funded warrants mentioned by Boundless Bio (BOLD)?

The amendment allows issuance of pre-funded warrants as part of the merger consideration instead of Boundless Bio common shares when issuing shares would cause a holder to exceed its Beneficial Ownership Limitation. These warrants have a per-share exercise price of $0.00001.

How did Boundless Bio (BOLD) change the voting standard for increasing authorized shares?

The increase in authorized Boundless Bio common shares will now require the affirmative vote of a majority of shares properly cast, instead of a majority of the shares outstanding and entitled to vote on the proposal.

What key risks to the Boundless Bio (BOLD) and Serapha merger are highlighted?

Risks include failure to satisfy closing conditions, timing and ability to complete the merger, potential non-consummation of the Company Pre-Closing Financing, regulatory approval delays, adjustments to the Exchange Ratio, changes to anticipated ownership percentages or cash dividend, and possible termination of the Merger Agreement.

Where can Boundless Bio (BOLD) investors find more details about the merger?

Investors can review Boundless Bio’s filings on the SEC’s website and on the company’s investor website. A Form S-4 registration statement with a proxy statement/prospectus will be filed and will contain detailed information about Boundless Bio, Serapha, and the proposed merger.

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

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Available on EDGAR 08/28/2026 - 05:26 PM EDT Accepted by SEC EDGAR 08/28/2026 - 05:25 PM EDT Learn about SEC filing dates

false 0001782303 0001782303 2026-08-28 2026-08-28

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 28, 2026

Boundless Bio, Inc.

(Exact Name of Registrant as Specified in Its Charter)

Delaware		001-41989		83-0751369
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(IRS Employer Identification No.)
11099 North Torrey Pines Road, Suite 150
La Jolla, California				92037
(Address of Principal Executive Offices)				(Zip Code)

Registrant’s Telephone Number, Including Area Code: (858) 766-9912

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☒ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, par value $0.0001 per share		BOLD		Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 1.01 Entry into a Material Definitive Agreement.

As previously announced, on June 22, 2026, Boundless Bio, Inc., a Delaware corporation (“Boundless Bio”), Boulder Merger Sub Corp., a Delaware corporation and wholly owned subsidiary of Boundless Bio (“Merger Sub”), and Serapha Bio, Inc., a Delaware corporation (“Serapha”), entered into an Agreement and Plan of Merger and Reorganization (as amended, the “Merger Agreement”), pursuant to which Merger Sub will be merged with and into Serapha, with Serapha surviving as a wholly owned subsidiary of Boundless Bio (the “Merger” and, together with all of the other transactions contemplated by the Merger Agreement, the “Contemplated Transactions”). Capitalized terms used but not otherwise defined in this Item 1.01 shall have the meanings ascribed to such terms in the Merger Agreement.

On August 28, 2026, the parties entered into Amendment No. 1 to the Merger Agreement (the “Amendment”). The Amendment amends the Merger Agreement to, among other things, (i) clarify certain definitions and provisions, including in relation to the Company Pre-Closing Financing; (ii) add mechanics for the treatment of Serapha restricted stock unit awards (“Serapha RSUs”), providing that each Serapha RSU (whether vested or unvested) outstanding immediately prior to the effective time of the Merger will be converted into a restricted stock unit award (an “Assumed RSU”) covering shares of Boundless Bio common stock, par value $0.0001 per share (“Boundless Bio Common Stock”), on generally the same terms and conditions, with the number of shares subject to each such Assumed RSU adjusted by the Exchange Ratio; (iii) add mechanics for the issuance of pre-funded warrants (with an exercise price of $0.00001 per share) as Merger Consideration in lieu of shares of Boundless Bio Common Stock to the extent the issuance of such shares would cause a holder to exceed its applicable Beneficial Ownership Limitation; and (iv) provide that the voting standard for the increase in the number of authorized shares of Boundless Bio Common Stock is the affirmative vote of a majority of the shares of Boundless Bio Common Stock properly cast, rather than the affirmative vote of a majority of the shares of Boundless Bio Common Stock outstanding and entitled to vote thereon.

Except as modified by the Amendment, the terms of the Merger Agreement in the form filed as Exhibit 2.1 to the Current Report on Form 8-K filed by Boundless Bio on June 23, 2026 with the U.S. Securities and Exchange Commission (the “SEC”) are unchanged.

The foregoing description of the Amendment is subject to, and is qualified in its entirety by, the full text of the Amendment filed as Exhibit 2.1 to this Current Report on Form 8-K, which is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number		Description
2.1		Amendment No. 1 to Agreement and Plan of Merger and Reorganization, dated August 28, 2026, by and among Boundless Bio, Inc., Boulder Merger Sub Corp., and Serapha Bio, Inc.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document)

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, statements regarding the structure and expectations of the consummation of the proposed Merger; expectations regarding the structure and completion of the Company Pre-Closing Financing; and other statements that are not historical fact. These forward-looking statements are made as of the date they were first issued, and were based on the then-current expectations, estimates, forecasts, and projections, as well as the beliefs and assumptions of management. There can be no assurance that future developments affecting Boundless Bio, Serapha or the Contemplated Transactions will be those that have been anticipated.

Forward-looking statements are subject to a number of risks and uncertainties, many of which involve factors or circumstances that are beyond Boundless Bio’s and Serapha’s control. Boundless Bio’s actual results could differ materially from those stated or implied in forward-looking statements due to a number of factors, including but not limited to (i) the risk that the conditions to the Closing are not satisfied; (ii) uncertainties as to the timing of the consummation of the proposed Merger and the ability of each of Boundless Bio and Serapha to consummate the proposed Merger; (iii) risks related to Boundless Bio’s ability to manage its operating expenses and its expenses associated with the proposed Merger pending Closing; (iv) risks related to the failure or delay in obtaining required approvals from any governmental or regulatory entity necessary to consummate the proposed Merger, if applicable; (v) the risk that as a result of adjustments to the Exchange Ratio, Boundless Bio’s stockholders and Serapha’s stockholders could own more or less of the combined company than is currently anticipated; (vi) risks related to the market price of Boundless Bio Common Stock relative to the value suggested by the Exchange Ratio and the anticipated cash dividend; (vii) unexpected costs, charges or expenses resulting from the proposed Contemplated Transactions; (viii) the risk that anticipated ownership percentages or cash dividend amount may change based on adjustments at or prior to closing; (ix) the risk that the Company Pre-Closing Financing is not consummated; (x) Serapha’s reliance on intellectual property rights under its license agreement with YolTech Therapeutics and risks related to the protection of intellectual property; and (xi) the potential for the occurrence of any event, change or other circumstance or condition that could give rise to the termination of the Merger Agreement and the other agreements entered into in connection therewith. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties. These and other risks and uncertainties are more fully described in periodic filings with the SEC, including the factors described in the section titled “Risk Factors” in Boundless Bio’s Annual Report on Form 10-K for the year ended December 31, 2025 and its Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, each filed with the SEC, and in other filings that Boundless Bio makes and will make with the SEC in connection with the proposed Merger, including the Proxy Statement (as defined below). You should not place undue reliance on these forward-looking statements, which are made only as of the date hereof or as of the dates indicated in the forward-looking statements. Boundless Bio expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in its expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based. This communication does not purport to summarize all of the conditions, risks and other attributes of an investment in Boundless Bio or Serapha.

Participants in the Solicitation

This Current Report on Form 8-K relates to the proposed Merger and other Contemplated Transactions involving Boundless Bio and Serapha and may be deemed to be solicitation material in respect of the proposed Merger and other Contemplated Transactions. In connection with the proposed Merger and other Contemplated Transactions, Boundless Bio will file relevant materials with the SEC, including the Form S-4 that will contain a proxy statement (the “Proxy Statement”) and prospectus. This communication is not a substitute for the Form S-4, the Proxy Statement or for any other document that Boundless Bio may file with the SEC and/or send to Boundless Bio’s stockholders in connection with the proposed Merger. Boundless Bio, Serapha, and their respective directors and certain of their executive officers may be considered participants in the solicitation of proxies from Boundless Bio’s stockholders with respect to the proposed Merger and other Contemplated Transactions under the rules of the SEC. Information about the directors and executive officers of Boundless Bio is set forth in its most recent definitive proxy statement filed with the SEC on April 28, 2026. Additional information regarding the persons who may be deemed participants in the proxy solicitations and a description of their direct and indirect interests, by security holdings or otherwise, will also be included in the Form S-4, the Proxy Statement and other relevant materials to be filed with the SEC when they become available. You may obtain free copies of this document as described below. BEFORE MAKING ANY VOTING DECISION, INVESTORS AND SECURITY HOLDERS OF BOUNDLESS BIO ARE URGED TO READ THE FORM S-4, THE PROXY STATEMENT AND OTHER DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT BOUNDLESS BIO, THE PROPOSED MERGER AND OTHER CONTEMPLATED TRANSACTIONS AND RELATED MATTERS.

No Offer or Solicitation

This Current Report on Form 8-K does not constitute an offer to sell or the solicitation of an offer to buy any securities nor a solicitation of any vote or approval with respect to the proposed transactions herein or otherwise. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act and otherwise in accordance with applicable law. BEFORE MAKING ANY VOTING DECISION, INVESTORS

AND SECURITY HOLDERS OF BOUNDLESS BIO ARE URGED TO READ THE FORM S-4, THE PROXY STATEMENT AND OTHER DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT BOUNDLESS BIO, THE PROPOSED MERGER AND OTHER CONTEMPLATED TRANSACTIONS AND RELATED MATTERS.

Additional Information and Where to Find It

Investors and security holders will be able to obtain free copies of the Form S-4, the Proxy Statement and other documents filed by Boundless Bio with the SEC through the website maintained by the SEC at http://www.sec.gov. Copies of the documents filed by Boundless Bio with the SEC will also be available free of charge on Boundless Bio’s website at investors.boundlessbio.com.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

						BOUNDLESS BIO, INC.
Date: August 28, 2026				By:		/s/ Jessica Oien
				Name:		Jessica Oien
				Title:		President, Chief Legal Officer and Corporate Secretary

Filing Exhibits & Attachments

4 documents

Other Documents

• EX-2.1 EX-2.1 124.2 KB
• EX-101 XBRL TAXONOMY EXTENSION SCHEMA 3.1 KB
• EX-101 XBRL TAXONOMY EXTENSION LABEL LINKBASE 18.3 KB
• EX-101 XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE 11.4 KB