Caldera Therapeutics, Synlogic (SYBX) outline merger and $278M financing
Rhea-AI Filing Summary
Synlogic, Inc. has agreed to combine with Caldera Therapeutics, Inc. in an all-stock transaction in which both companies become wholly owned subsidiaries of a new holding company that will operate as Caldera Therapeutics and seek listing on Nasdaq under the symbol “CALD.” At Closing, pre-merger Caldera equityholders are expected to own 62.8% of the combined company, pre-merger Synlogic equityholders 2.3%, and investors in a concurrent financing 34.9%, based on a $500.0 million valuation for Caldera and $18.0 million for Synlogic (assuming $6.0 million Synlogic net cash), with percentages subject to adjustment.
Caldera has entered into a Securities Purchase Agreement for a concurrent private placement of approximately $278.0 million of Caldera common stock, with proceeds and existing cash expected to fund CLD-423 through Phase 2 trials in ulcerative colitis and Crohn’s disease and provide cash runway into 2029. Stockholders holding about 50.9% of Synlogic and 72.6% of Caldera have signed support agreements, and certain Caldera insiders agreed to 180‑day lock-ups on Parent stock.
Conditions to Closing include Synlogic and Caldera stockholder approvals, effectiveness of a Form S‑4 registration statement, listing approval for Parent common stock on Nasdaq, completion of the Concurrent Financing with at least $278.0 million in cash proceeds, maintenance of Synlogic’s OTC Pink quotation, and absence of continuing material adverse effects. Caldera may owe a $5.0 million termination fee and Synlogic a $1.0 million fee in specified deal-failure scenarios. Separately, Synlogic amended warrants on 7,394,363 shares to cut the exercise price from $3.408 to $0.70 and removed holders’ cash redemption right on a fundamental transaction.
Positive
- A concurrent private placement of approximately $278.0 million is expected to fund CLD-423 Phase 2 development in ulcerative colitis and Crohn’s disease and provide cash runway for the combined company into 2029.
Negative
- Legacy Synlogic stockholders are expected to hold only 2.3% of the combined company at Closing, a much smaller stake than Caldera holders and new investors.
Filing Explained
The merger is not yet closed: option treatment is set at closing, while financing investors receive a post-closing resale-registration obligation rather than an immediate sale.
The Synlogic–Caldera merger agreement is signed but not closed; its holder mechanics determine whether each Synlogic option becomes fully vested and net-exercised into Parent shares or remains an adjusted Parent option.
Options priced below Synlogic’s closing trading price on the last full trading day before the Synlogic Effective Time become fully vested and net-exercised into Parent shares; options priced above that level are assumed and converted into Parent options on their existing vesting and exercisability terms.
Separately, the post-closing company must file a resale registration statement for the concurrent-financing investors within 30 calendar days after the Closing Date; that filing is a registration obligation, not a disclosure that the investors have sold their shares.
8-K Event Classification
Key Figures
Key Terms
Agreement and Plan of Merger regulatory
Form S-4 regulatory
Concurrent Financing financial
Registration Rights Agreement regulatory
Warrant Amending Agreements financial
termination fee financial
AI-generated analysis. How Rhea-AI works. Not financial advice.
FAQ
What transaction is Synlogic (SYBX) announcing with Caldera Therapeutics?
How will ownership of the combined company be split for SYBX stockholders?
What is the size and purpose of Caldera’s concurrent financing in the Synlogic (SYBX) deal?
What are the main conditions that must be met before the Synlogic–Caldera merger closes?
How are Synlogic’s outstanding warrants affected by this 8-K transaction?
What termination fees apply if the Synlogic–Caldera merger is not completed?
What will the combined Synlogic–Caldera company focus on after the merger?
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM
CURRENT REPORT
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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 |
Merger Agreement
On July 28, 2026, Synlogic, Inc., a Delaware corporation (“Synlogic”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) by and among Synlogic, Caldera Therapeutics, Inc., a Delaware corporation (“Caldera”), Sonic Holdco, Inc., a Delaware corporation (“Parent”), Yellowstone Merger Sub, Inc., a Delaware corporation and a direct, wholly owned subsidiary of Parent (“Caldera Merger Sub”), and Sonic Merger Sub, Inc., a Delaware corporation and a direct, wholly owned subsidiary of Parent (“Synlogic Merger Sub”).
Pursuant to the Merger Agreement, and upon the terms and subject to the satisfaction of the conditions described therein, Synlogic will be merged with and into Synlogic Merger Sub, with Synlogic surviving as a wholly owned subsidiary of Parent (the “Synlogic Merger”), and Caldera will be merged with and into Caldera Merger Sub, with Caldera surviving as a wholly owned subsidiary of Parent (the “Caldera Merger” and, together with the Synlogic Merger, the “Mergers” and, together with all of the other transactions contemplated by the Merger Agreement, the “Contemplated Transactions”). The Mergers are intended to qualify as a tax-free reorganization for U.S. federal income tax purposes.
Subject to the terms and conditions of the Merger Agreement, (a) at the effective time of the Caldera Merger (the “Caldera Effective Time”) and following the conversion into shares of common stock of Caldera, $0.0001 par value per share (“Caldera Common Stock”) of Caldera’s (i) Series A Preferred Stock, $0.00001 par value per share, and (ii) Series A-1 Preferred Stock, $0.00001 par value per share, each then-outstanding share of Caldera Common Stock, including shares of Caldera Common Stock issued in connection with the Concurrent Financing (as defined below) (excluding any shares of Caldera Common Stock held by stockholders who have exercised and perfected appraisal rights for such shares) will be converted into the right to receive a number of shares of common stock of Parent, $0.001 par value per share (“Parent Common Stock”), calculated in accordance with the applicable exchange ratio as set forth in the Merger Agreement and (b) immediately following the Caldera Effective Time, at the effective time of the Synlogic Merger (the “Synlogic Effective Time”), each then-outstanding share of common stock of Synlogic, $0.001 par value per share (the “Synlogic Common Stock”) (excluding any shares of Synlogic Common Stock held by stockholders who have exercised and perfected appraisal rights for such shares) will be converted into the right to receive a number of shares of Parent Common Stock, calculated in accordance with the applicable exchange ratio as set forth in the Merger Agreement.
At the Synlogic Effective Time, each then-outstanding option to purchase shares of Synlogic Common Stock (a “Synlogic Option”) with an exercise price per share less than the closing trading price of a share of Synlogic Common Stock, on the last full trading day on which the Synlogic Common Stock is traded prior to the date on which the Synlogic Effective Time occurs, will become fully vested and converted into net-exercised shares of Parent Common Stock, subject to adjustment as set forth in the Merger Agreement. At the Synlogic Effective Time, each then-outstanding option to purchase Synlogic Common Stock with an exercise price per share greater than the closing trading price of a share of Synlogic Common Stock, on the last full trading day on which the Synlogic Common Stock is traded prior to the date on which the Synlogic Effective Time occurs, will be immediately prior to the Synlogic Effective Time, assumed and converted into an option to purchase Parent Common Stock, on the same terms and conditions (including the same vesting and exercisability terms and conditions) as were applicable to such Synlogic Option immediately prior to the Synlogic Effective Time, subject to adjustment as set forth in the Merger Agreement.
Each then-outstanding option to purchase Caldera Common Stock (a “Caldera Option”) will be immediately prior to the Caldera Effective Time, assumed and converted into an option to purchase Parent Common Stock, on the same terms and conditions (including the same vesting and exercisability terms and conditions) as were applicable to such Caldera Option immediately prior to the Caldera Effective Time, subject to adjustment as set forth in the Merger Agreement.
At the Closing (as defined below), on a pro forma basis and based upon the number of shares of Parent Common Stock expected to be issued in connection with the Mergers and the Concurrent Financing, pre-merger equityholders of Caldera (other than the Investors (as defined below) in the Concurrent Financing) are expected to own approximately 62.8% of the combined company, pre-merger equityholders of Synlogic are expected to own approximately 2.3% of the combined company and the Investors in the Concurrent Financing are expected to own approximately 34.9% (assuming proceeds from the Concurrent Financing of $278.0 million), in each case, calculated on a fully diluted basis, using the treasury stock method, and subject to certain assumptions, including (i) a valuation for Synlogic of $18.0 million, assuming Synlogic has net cash of $6.0 million as of the closing of the Mergers (the “Closing” and such date, the “Closing Date”), (ii) a valuation for Caldera of $500.0 million, and (iii) the relative capitalization of Synlogic and Caldera. The percentage of the combined company that each party’s equity holders will own following the Closing is subject to certain adjustments as described in the Merger Agreement, including the amount of the Final Synlogic Net Cash at Closing (as defined in the Merger Agreement).
The Merger Agreement contains representations and warranties of the parties regarding their respective businesses. The Merger Agreement also contains certain covenants made by each of Synlogic and Caldera, including non-solicitation restrictions binding each party (and subject to certain exceptions as further described in the Merger Agreement) and its representatives and restrictions on the operation of each party’s business between the date of the Merger Agreement and the Closing.
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In connection with the Mergers, Parent will prepare and file a registration statement on Form S-4, which will contain a prospectus to register the shares of Parent Common Stock issued pursuant to the Merger Agreement (the “Form S-4”). Promptly after the Form S-4 is declared effective, Synlogic shall hold a stockholder meeting to seek the vote of Synlogic’s stockholders of, among other matters, the approval of the Merger Agreement and the Contemplated Transactions, including the Synlogic Merger (the “Synlogic Stockholder Approval”) and Caldera shall solicit written consents from the Caldera stockholders (the “Caldera Stockholder Written Consent”) to seek approval of the Merger Agreement and the Contemplated Transactions, including the Caldera Merger.
The Closing is subject to certain closing conditions, including: (i) the Synlogic Stockholder Approval; (ii) approval by the requisite Caldera stockholders of the adoption and approval of the Merger Agreement and the transactions contemplated thereby; (iii) the approval of the listing of the shares of Parent Common Stock to be issued in the Mergers on The Nasdaq Stock Market; (iv) the Securities Purchase Agreement (as defined below) being in full force and effect with cash proceeds of no less than $278.0 million having been received by Caldera; (v) the existing shares of Synlogic Common Stock having remained quoted on the OTC Pink Limited Market as of and from the date of the Merger Agreement through the Closing Date; and (vi) the effectiveness of the Form S-4. The Closing is also subject to other specified customary closing conditions of each party, including the accuracy of each party’s representations and warranties, subject to applicable materiality qualifications, compliance by each party with its covenants under the Merger Agreement in all material respects, respectively, delivery of certain customary closing documents by each of Synlogic and Caldera, and no Synlogic material adverse effect or Caldera material adverse effect having occurred since the date of the Merger Agreement that is continuing, respectively.
Either party may be required to pay a termination fee in the event of termination of the Merger Agreement in certain circumstances. A termination fee of $5.0 million (the “Caldera Termination Fee”) may become payable by Caldera to Synlogic if the Merger Agreement is terminated by (a) Synlogic if a Caldera Triggering Event (as defined in the Merger Agreement) shall have occurred, which includes (i) the board of directors of Caldera or a committee thereof makes a Caldera Board Adverse Recommendation Change (as defined in the Merger Agreement), or (ii) Caldera’s entry into a letter of intent or other agreement relating to an alternative acquisition proposal, or (b) by Caldera concurrently with Caldera’s entry into any Permitted Alternative Agreement (as defined in the Merger Agreement), subject to certain requirements set forth in the Merger Agreement. In addition, the Caldera Termination Fee may also become payable by Caldera to Synlogic on a “tail” basis if the Merger Agreement is terminated (i) because the Mergers were not consummated by six months from the date of the Merger Agreement (the “Outside Date”) or Caldera fails to obtain the approval of its stockholders for the Contemplated Transactions and deliver such approval to Synlogic within 15 days after the Form S-4 becomes effective, or (ii) upon Caldera’s uncured material breach of the Merger Agreement and consummation of an alternative acquisition transaction within twelve months after such termination.
A termination fee of $1.0 million (the “Synlogic Termination Fee”) may become payable by Synlogic to Caldera if the Merger Agreement is terminated (a) by Caldera if a Synlogic Triggering Event (as defined in the Merger Agreement) shall have occurred, which includes (i) the failure of Synlogic to include the Synlogic Board Recommendation (as defined in the Merger Agreement) in its proxy statement, (ii) the board of directors of Synlogic or a committee thereof makes a Synlogic Board Adverse Recommendation Change (as defined in the Merger Agreement), or (iii) Synlogic’s entry into a letter of intent or other agreement relating to an alternative acquisition proposal, or (b) by Synlogic concurrently with Synlogic’s entry into any Permitted Alternative Agreement, subject to certain requirements set forth in the Merger Agreement. In addition, the Synlogic Termination Fee may also become payable by Synlogic to Caldera on a “tail” basis if the Merger Agreement is terminated (i) because the Mergers were not consummated by the Outside Date or Synlogic fails to obtain the approval of its stockholders for the Contemplated Transactions, or (ii) by Caldera upon Synlogic’s uncured material breach of the Merger Agreement and consummation of an alternative acquisition transaction within twelve months after such termination.
Support Agreements
Concurrently with the execution of the Merger Agreement, certain stockholders of Synlogic holding approximately 50.9% of the outstanding Synlogic capital stock entered into support agreements (the “Synlogic Support Agreements”) in favor of Caldera, providing among other things, that such stockholders will vote all of their eligible shares of Synlogic capital stock, among other things: (i) in favor of approving the Mergers, the Synlogic Stockholder Approval and the other actions contemplated by the Merger Agreement and (ii) against any proposal made in opposition to, or in competition with, the Merger Agreement or the Mergers.
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Concurrently with the execution of the Merger Agreement, certain stockholders of Caldera holding approximately 72.6% of the outstanding Caldera capital stock entered into support agreements (the “Caldera Support Agreements” and, together with the Synlogic Support Agreements, the “Support Agreements”) in favor of Caldera, providing among other things, that such stockholders will vote all of their shares of Caldera capital stock, among other things: (i) in favor of approving the Mergers, the Caldera Stockholder Written Consent and the other actions contemplated by the Merger Agreement and (ii) against any proposal made in opposition to, or in competition with, the Merger Agreement or the Mergers.
Lock-Up Agreements
Concurrently with the execution of the Merger Agreement, the executive officers, directors and certain stockholders of Caldera entered into lock-up agreements (the “Lock-Up Agreements”), pursuant to which, subject to specified exceptions, such persons accepted certain restrictions on transfers of the shares of Parent Common Stock beneficially held by such persons or such persons’ family members (other than shares received as a result of the conversion of shares received in the Concurrent Financing) for the 180-day period following the Synlogic Effective Time.
The foregoing descriptions of the Merger Agreement, the form of Synlogic Support Agreement, the form of the Caldera Support Agreement and the form of Lock-Up Agreement (collectively, the “Agreements”), do not purport to be complete and are qualified in their entirety by reference to those Agreements, which are filed as Exhibits 2.1, 10.1, 10.2 and 10.3, respectively, to this Current Report on Form 8-K and incorporated herein by reference. In particular, the assertions embodied in the representations and warranties contained in the Merger Agreement are qualified by information in confidential disclosure schedules provided by each of Parent, Synlogic and Caldera in connection with the signing of the Merger Agreement. These confidential disclosure schedules contain information that modifies, qualifies and creates exceptions to the representations and warranties and certain covenants set forth in the Merger Agreement. Moreover, certain representations and warranties in the Agreements were used for the purpose of allocating risk between the parties thereto rather than establishing matters as facts. Accordingly, the representations and warranties may not describe the actual state of affairs at the date they were made or at any other time, and investors should not rely on them as statements of fact.
Concurrent Financing
Concurrently with entering into the Merger Agreement, Caldera entered into a securities purchase agreement (the “Securities Purchase Agreement”) with certain qualified institutional buyers and/or accredited investors (the “Investors”). Pursuant to the Securities Purchase Agreement, and subject to the terms and conditions therein, Caldera agreed to sell, and the Investors agreed to purchase, an aggregate of approximately $278.0 million worth of shares of Caldera Common Stock (the “Concurrent Financing”). The price per share is equal to the Caldera Equity Value (as defined in the Merger Agreement) divided by the number of shares of Caldera Common Stock outstanding as of immediately prior to the Closing. Shares of Caldera Common Stock issued pursuant to the Concurrent Financing will be converted into shares of Parent Common Stock, in accordance with the terms of the Merger Agreement. The closing of the Concurrent Financing is anticipated to occur on or about the date of the Closing of the Mergers, subject to the satisfaction of customary closing conditions, including (i) Caldera’s receipt of aggregate proceeds under the Securities Purchase Agreement of not less than $278.0 million, (ii) that the closing of the Mergers shall be set to occur substantially concurrently with the closing under the Securities Purchase Agreement, and (iii) that Synlogic shall have obtained the stockholder approval required under the Merger Agreement. The Securities Purchase Agreement contains customary representations and warranties of Caldera, on the one hand, and the Investors, on the other hand, and customary indemnification provisions.
Parent and Caldera have also entered into a registration rights agreement (the “Registration Rights Agreement”) with the Investors in connection with the Concurrent Financing. Pursuant to the Registration Rights Agreement, the combined company will prepare and file a resale registration statement with the Securities and Exchange Commission (the “SEC”) within 30 calendar days following the Closing Date. The combined company will use its reasonable best efforts to cause such registration statement to become effective at the earliest possible date.
The combined company will also agree to, among other things, indemnify the Investors, their members, shareholders, directors, officers, partners, employees, managers, agents, representatives and advisors under the Registration Rights Agreement from certain liabilities and pay all fees and expenses (excluding underwriting discounts and selling commissions and all similar fees and commissions relating to an Investor’s disposition of its Registrable Securities (as defined in the Registration Rights Agreement)) incident to the combined company’s obligations under the Registration Rights Agreement.
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The foregoing descriptions of the Securities Purchase Agreement and Registration Rights Agreement do not purport to be complete and are qualified in their entirety by reference to the Securities Purchase Agreement, as well as the Registration Rights Agreement, forms of which are filed as Exhibits 10.4 and 10.5, respectively, to this Current Report on Form 8-K and are incorporated herein by reference.
Warrant Amending Agreements
In October 2023, in an underwritten public offering, Synlogic issued to certain purchasers (the “Holders”) common warrants (the “Warrants”) to purchase up to an aggregate of 7,394,363 shares of Synlogic Common Stock (the “Warrant Shares”) exercisable at $3.408 per share, subject to adjustment (the “Exercise Price”). On July 27, 2026, Synlogic entered into warrant amending agreements (collectively, the “Warrant Amending Agreements”) with all the Holders that (i) reduced the Exercise Price of the Warrants to $0.70 per Warrant Share and (ii) removed the Holders’ right to require Synlogic or a successor entity to redeem the Warrants for cash in an amount equal to the Black-Scholes Value (as defined in the Warrants) of the unexercised portion thereof, concurrently with or within 30 days following the consummation of a fundamental transaction.
The foregoing description of the Warrant Amending Agreements does not purport to be complete and is qualified in its entirety by reference to the form of Warrant Amending Agreement, which is filed as Exhibit 10.6 to this Current Report on Form 8-K and is incorporated herein by reference.
| Item 3.03 | Material Modifications to Rights of Security Holders |
To the extent required by this Item, the information included in Item 1.01 of this Current Report on Form 8-K is incorporated by reference herein.
| Item 5.01 | Changes in Control of Registrant |
To the extent required by this Item, the information included in Item 1.01 of this Current Report on Form 8-K is incorporated herein by reference.
| Item 7.01 | Regulation FD Disclosure |
On July 29, 2026, Synlogic and Caldera issued a joint press release announcing the execution of the Merger Agreement and the Securities Purchase Agreement. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K.
The information in Item 7.01 of this Current Report on Form 8-K, including the information in the press release attached as Exhibit 99.1, is furnished pursuant to Item 7.01 of Form 8-K and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section. Furthermore, the information in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1 to this Current Report on Form 8-K, shall not be deemed to be incorporated by reference in the filings of Synlogic under the Securities Act of 1933, as amended (the “Securities Act”).
Use of Website to Distribute Material Non-Public Information
Synlogic’s Investor Relations website is www.investor.synlogictx.com. Synlogic uses its Investor Relations website as a means of disclosing material non-public information and for the purpose of complying with its disclosure obligations under Regulation FD. Therefore, Synlogic encourages investors, the media and others interested in Synlogic to review the information it posts on its Investor Relations website.
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Additional Information and Where to Find It
In connection with the Contemplated Transactions between Caldera and Synlogic, Synlogic and the Parent will file relevant materials with the SEC. The Parent will file a registration statement on Form S-4 that will include a proxy statement and prospectus relating to the Contemplated Transactions, which will constitute a proxy statement of Synlogic and a prospectus of the Parent (the “Prospectus”). Synlogic and the Parent may also file other documents with the SEC regarding the Contemplated Transactions. This document is not a substitute for the Prospectus or any other document which Synlogic or the Parent may file with the SEC or send to stockholders of Synlogic or Caldera in connection with the Contemplated Transactions. The Prospectus will be mailed to stockholders of Synlogic. INVESTORS AND SECURITYHOLDERS OF SYNLOGIC ARE URGED TO READ THE REGISTRATION STATEMENT AND THE PROSPECTUS AND ALL OTHER DOCUMENTS FILED OR THAT WILL BE FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT SYNLOGIC, CALDERA AND THE CONTEMPLATED TRANSACTIONS. Investors and security holders will be able to obtain free copies of the registration statement and the Prospectus (when available) and other documents filed with the SEC by Synlogic or the Parent through the website maintained by the SEC at www.sec.gov. Copies of the documents filed with the SEC by Synlogic will be available free of charge on Synlogic’s website at www.synlogictx.com.
No Offer or Solicitation
This communication is for informational purposes only and not intended to and does not constitute an offer to subscribe for, buy or sell, or the solicitation of an offer to subscribe for, buy or sell, or an invitation to subscribe for, buy or sell, any securities of Synlogic, Caldera or the Parent, or the solicitation of any vote or approval in any jurisdiction pursuant to or in connection with the Contemplated Transactions or otherwise, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in contravention of applicable law. No offer 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.
Participants in the Solicitation
This communication is not a solicitation of a proxy from any security holder of Synlogic or Caldera. However, Synlogic, Caldera and the Parent and each of their respective directors and executive officers may be considered participants in the solicitation of proxies in connection with the Contemplated Transactions. Information about the directors and executive officers of Synlogic may be found in its Annual Report on Form 10-K for the year ended December 31, 2025, which was filed with the SEC on March 12, 2026, as amended by our Annual Report on Form 10-K/A, filed with the SEC on April 30, 2026. Other information regarding the participants in the proxy solicitations and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the prospectus and other relevant materials to be filed with the SEC when they become available.
Cautionary Statements Regarding Forward-Looking Statements
This Current Report on Form 8-K contains “forward-looking statements” within the meaning of the federal securities laws, including Section 27A of the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended. In this context, forward-looking statements often address expected future business and financial performance and often contain words such as “expect,” “anticipate,” “intend,” “plan,” “believe,” “seek,” “will,” “would,” “target,” and similar expressions. Forward-looking statements by their nature address matters that involve risks and uncertainties, many of which are beyond Synlogic’s control and are not guarantees of future results, including statements about the Contemplated Transactions, the Concurrent Financing, future financial and operating results, and combined company strategy and operations. These forward-looking statements reflect management’s good faith judgment based on facts and factors currently known to management. Synlogic cautions investors not to place undue reliance on any such forward-looking statements.
These and other forward-looking statements are not guarantees of future results and are subject to risks, uncertainties and assumptions that could cause actual results to differ materially from those expressed in any forward-looking statements. These risks include, but are not limited to, risks and uncertainties related to: (i) the ability to obtain the requisite approval from stockholders of Synlogic and Caldera; (ii) the risk that the Contemplated Transactions and the Concurrent Financing may not be completed in a timely manner or at all; (iii) the possibility that competing offers or acquisition proposals will be made; (iv) the possibility that any or all of the various conditions to the consummation of the Contemplated Transactions and the Concurrent Financing may not be satisfied or waived, including the failure
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to receive any required regulatory approvals from any applicable governmental entities; (v) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement, including in circumstances that would require either party to pay a termination fee or other expenses; (vi) the effect of the pendency of the Contemplated Transactions on the parties’ ability to retain and hire key personnel, their ability to maintain relationships with customers, suppliers and others with whom they do business, their business generally or their stock price; (vii) risks related to diverting management’s attention from ongoing business operations or the loss of one or more members of the management team; (viii) the risk that stockholder litigation in connection with the Contemplated Transactions may result in significant costs of defense, indemnification and liability; (ix) the parties’ ability to realize the anticipated benefits of the Contemplated Transactions; (x) the risk that the parties may assume unexpected liabilities and expenses as a result of the Contemplated Transactions and the Concurrent Financing; (xi) uncertainties as to Caldera’s anticipated preclinical and clinical drug development activities and related timelines, including the expected timing for commencing clinical trials and announcing data and other clinical results; (xii) the risk that interim, preliminary or topline clinical data may change as additional data become available, and that early clinical results may not be predictive of results in later-stage clinical trials or in patients; and (xiii) uncertainties regarding the safety, efficacy, immunogenicity, pharmacokinetic profile and regulatory path of CLD-423, including interactions with and approvals from applicable regulatory authorities. For information regarding other related risks, see the “Risk Factors” section of Synlogic’s Annual Report on Form 10-K for the year ended December 31, 2025, filed with the SEC on March 12, 2026, as amended on April 30, 2026, Synlogic’s most recent Quarterly Report on Form 10-Q and Synlogic’s other filings with the SEC. Should any of these risks or uncertainties materialize, actual results could differ materially from expectations. These forward-looking statements speak only as of the date hereof. Neither Synlogic nor Caldera assumes any obligation to, and does not currently intend to, update any such forward-looking statements except as may be required by law.
| Item 9.01 | Financial Statements and Exhibits |
| Exhibit No. |
Description | |
| 2.1* | Agreement and Plan of Merger, dated as of July 28, 2026, by and among Synlogic, Inc., Caldera Therapeutics, Inc., Sonic Holdco, Inc., Yellowstone Merger Sub, Inc., and Sonic Merger Sub, Inc. | |
| 10.1 | Form of Synlogic Stockholder Support Agreement | |
| 10.2 | Form of Caldera Stockholder Support Agreement | |
| 10.3 | Form of Lock-Up Agreement | |
| 10.4* | Form of Securities Purchase Agreement | |
| 10.5 | Form of Registration Rights Agreement | |
| 10.6 | Form of Warrant Amending Agreement | |
| 99.1 | Press Release issued on July 29, 2026 | |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document). | |
| * | Certain schedules and attachments have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The Company agrees to provide, on a supplemental basis, a copy of any omitted schedules and attachments to the Securities and Exchange Commission or its staff upon request. |
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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 thereunto duly authorized.
| Date: July 29, 2026 | SYNLOGIC, INC. | |||||
| By: | /s/ Mary Beth Dooley | |||||
| Name: | Mary Beth Dooley | |||||
| Title: | Principal Executive Officer and Principal Financial Officer | |||||
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Exhibit 99.1
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Synlogic and Caldera Therapeutics Announce Merger Agreement and Concurrent Private Placement
July 29, 2026
Combined company to operate as Caldera Therapeutics, developing CLD-423, a potential first-in-class
TL1A x IL-23p19 bispecific antibody for inflammatory bowel disease and other immune-mediated diseases
Concurrent upsized $278 million private placement committed by a syndicate of leading healthcare
institutional investors and mutual funds expected to fund operations through Phase 2 clinical trials in
ulcerative colitis and Crohn’s disease, with cash runway projected into 2029
CAMBRIDGE, Mass., July 29, 2026 – Synlogic, Inc. (OTC: SYBX) (“Synlogic”) and Caldera Therapeutics, Inc. (“Caldera”), a privately held clinical-stage biotechnology company developing CLD-423, a potential first-in-class TL1A x IL-23p19 bispecific antibody for inflammatory bowel disease (IBD) and other immune-mediated diseases, today announced that they have entered into a definitive merger agreement to combine in an all-stock transaction. The combination will be accomplished by both companies becoming wholly-owned subsidiaries of a newly formed holding company. Upon closing, the combined company plans to operate under the name Caldera Therapeutics, Inc. and intends to apply to trade on the Nasdaq Capital Market under the ticker symbol “CALD.”
In support of the proposed merger, Caldera has secured commitments for an upsized concurrent private placement expected to generate approximately $278 million in gross proceeds from a syndicate of leading healthcare institutional investors and mutual funds, including Bain Capital Life Sciences, TCGX, Atlas Venture, venBio Partners, Omega Funds, Blackstone Multi-Asset Investing, LAV, Wellington Management, Janus Henderson Investors, Sirenia Capital Management LP, Vivo Capital, several additional mutual funds and other institutional investors.
The financing is expected to support the Phase 2 clinical development of CLD-423 in ulcerative colitis and Crohn’s disease, as well as potential development in additional immune-mediated diseases. The combined company’s cash and cash equivalents at closing, together with the proceeds from the concurrent private placement, are expected to fund the combined company’s operations into 2029. The financing is expected to close concurrently with the merger, subject to the satisfaction of customary closing conditions.
“In just over a year, we’ve shown our team’s ability to open up a lead with compelling data from a molecule poised to deliver the next horizon of I&I therapy,” said Praveen Tipirneni, MD, MBA, Chief Executive Officer of Caldera. “These transactions provide the capital and public company platform to advance our vision as we move into Phase 2 development in IBD and continue exploring the potential of CLD-423 across additional immune-mediated diseases.”
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“Following our evaluation of strategic alternatives, we believe this transaction represents the best path forward for our shareholders and an exciting opportunity to support the advancement of an innovative program with the potential to break through the current efficacy ceiling in inflammatory bowel disease,” said Mary Beth Dooley, Principal Executive Officer and Principal Financial Officer of Synlogic. “We are impressed by the strength of Caldera’s team, CLD-423’s differentiated profile, and the clear development strategy for the combined company. We look forward to supporting this next chapter and the important work ahead.”
About CLD-423
CLD-423 is an investigational bispecific antibody designed to simultaneously inhibit the clinically validated TL1A and IL-23p19 pathways for the treatment of inflammatory bowel disease (IBD) and other immune-mediated diseases. By combining both mechanisms in one molecule, CLD-423 has the potential to deliver greater efficacy than single-targeted standards of care. CLD-423 was rationally designed with a natural IgG structure and a monovalent 1+1 format to reduce TL1A target-based immunogenicity liabilities. In addition, CLD-423 incorporates the YTE half-life extension mutation to enable a competitive dosing profile.
CLD-423 is currently being evaluated in a Phase 1 healthy volunteer clinical trial in Australia. The trial commenced in January 2026 and has completed dosing. Unblinded data from the first four single ascending dose (SAD) cohorts through 85 days (cohorts 1 and 2) and 57 days (cohorts 3 and 4) support trial objectives and provide a strong foundation for future efficacy trials. In these SAD cohorts, CLD-423 was generally well tolerated with no dose-limiting toxicities. CLD-423 demonstrated a favorable pharmacokinetic (PK) profile, with approximately dose-proportional exposure, a serum half-life exceeding 40 days within the anticipated therapeutic exposure range, and approximately 80% subcutaneous bioavailability. These properties support the potential for a convenient maintenance dosing regimen of once every 8 or 12 weeks in IBD patients. CLD-423 demonstrated rapid and sustained TL1A target engagement as measured by inhibition of pNF-kB signaling in whole blood. Anti-drug antibody (ADA) incidence was low in the SAD cohorts, with late onset and low titers, reflecting a favorable immunogenicity profile consistent with well-behaved therapeutic antibodies and not characteristic of bivalent anti-TL1A antibodies. Caldera expects to report additional data from all five SAD cohorts and data from the multiple-dose cohorts later in 2026.
Caldera holds exclusive worldwide rights to develop and commercialize CLD-423 under a license agreement with Qyuns Therapeutics Co., Ltd. Caldera plans to initially develop CLD-423 in ulcerative colitis and Crohn’s disease before potentially expanding into additional immune-mediated diseases.
About the Proposed Transaction
Under the terms of the merger agreement, as of the closing of the proposed merger, pre-merger Synlogic stockholders are expected to own approximately 2.3% of the combined company, pre-merger Caldera stockholders are expected to own approximately 62.8% of the combined company, and investors participating in the concurrent private placement are expected to own approximately 34.9% of the combined company.
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The percentage ownership of the combined company that Synlogic stockholders will own as of the closing of the proposed merger is subject to adjustment based on the estimated amount of Synlogic’s net cash immediately prior to the closing date.
The transaction has been approved by the Board of Directors of both companies and is expected to close by early 2027, subject to the satisfaction of customary closing conditions, including, among others, approval by the stockholders of each company, the effectiveness of a registration statement to be filed with the U.S. Securities and Exchange Commission (“SEC”) to register the securities to be issued in connection with the proposed acquisitions of Caldera and Synlogic and the satisfaction of other customary closing conditions.
Following the closing, the combined company will operate under the name Caldera Therapeutics, Inc. and intends to apply to trade on the Nasdaq Capital Market under the ticker symbol “CALD.” The combined company will be led by Praveen Tipirneni, MD, MBA, Caldera’s current Chief Executive Officer. Caldera’s Board of Directors will become the directors of the combined company.
Lucid Capital Markets is serving as exclusive financial advisor to Synlogic, and Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. is serving as legal counsel to Synlogic.
Jefferies, TD Cowen, Guggenheim Securities, UBS Investment Bank, and LifeSci Capital are serving as placement agents to Caldera. Fenwick & West LLP is serving as legal counsel to Caldera. Cooley LLP is serving as legal counsel to the placement agents.
About Caldera Therapeutics, Inc.
Caldera Therapeutics is a clinical-stage company developing CLD-423, a potential first-in-class bispecific antibody targeting the clinically validated IL-23p19 and TL1A pathways for the treatment of inflammatory bowel disease (IBD) and other immune-mediated diseases. Caldera has assembled a senior leadership team with deep experience in the discovery and development of IBD therapeutics and a proven track record of building biotechnology companies.
About Synlogic
Synlogic is a biopharmaceutical company historically focused on advancing novel therapeutics to transform the care of serious disease in need of new treatment options.
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Important Additional Information and Where to Find It
In connection with the proposed transaction between Caldera and Synlogic, Synlogic and the newly formed company will file relevant materials with the SEC. The newly formed company will file a registration statement on Form S-4 that will include a proxy statement and prospectus relating to the proposed transaction, which will constitute a proxy statement of Synlogic and a prospectus of the newly formed company (the “Prospectus”). Synlogic and the newly formed company may also file other documents with the SEC regarding the proposed transaction. These documents are not a substitute for the Prospectus or any other document which Synlogic or the newly formed company may file with the SEC or send to stockholders of Synlogic or Caldera in connection with the proposed transaction. The Prospectus will be mailed to Synlogic’s stockholders.
INVESTORS AND SECURITY HOLDERS OF SYNLOGIC AND CALDERA ARE URGED TO READ THE PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS FILED OR THAT WILL BE FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION REGARDING SYNLOGIC, CALDERA, AND THE PROPOSED TRANSACTION.
Investors and security holders will be able to obtain free copies of the registration statement and the Prospectus (when available) and other documents filed with the SEC by Synlogic or the newly formed company through the website maintained by the SEC at www.sec.gov. Copies of the documents filed with the SEC by Synlogic will be available free of charge on Synlogic’s website at www.synlogictx.com.
No Offer or Solicitation
This communication is for informational purposes only and not intended to constitute, and shall not constitute, an offer to subscribe for, buy or sell, or the solicitation of an offer to subscribe, buy, or sell, any securities of Caldera, Synlogic, or the combined company, or the solicitation of any vote or approval in any jurisdiction for the proposed merger or otherwise, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in contravention of applicable law. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended, and otherwise in accordance with applicable law.
Participants in the Solicitation
This communication is not a solicitation of a proxy from any security holder of Synlogic or Caldera. However, Synlogic and Caldera and each of their respective directors and executive officers may be considered participants in the solicitation of proxies in connection with the proposed transaction. Information about the directors and executive officers of Synlogic may be found in its Annual Report on Form 10-K for the year ended December 31, 2025, which was filed with the SEC on March 12, 2026 and its Amendment to its Annual Report on Form 10-K for the year ended December 31, 2025, which was filed with the SEC on April 30, 2026. Other information regarding the participants in the proxy solicitations and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the Prospectus and other relevant materials to be filed with the SEC when they become available.
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Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including, among others, statements regarding the expected timing of the closing of the transaction; the potential benefits of the proposed transaction; the prospective performance and outlook of the combined company’s business, performance and opportunities; the ability of the parties to complete the proposed transaction; the competitive position of the combined company; the expected post-closing ownership of the combined company; the expected management team and Board of Directors of the combined company; the combined company’s expected cash at closing and cash runway; the therapeutic potential of CLD-423 and its safety, tolerability, pharmacokinetic, pharmacodynamic and immunogenicity profile, including the anticipated benefits of its design; the interpretation and significance of interim and preliminary data from Caldera’s ongoing and planned clinical trials of CLD-423; the estimated half-life of CLD-423 and its potential for extended subcutaneous maintenance dosing; the design, timing, initiation, enrollment, endpoints and anticipated results of Caldera’s current and planned clinical trials and preclinical studies, and the timing of related regulatory submissions and interactions with applicable regulatory authorities; the potential of CLD-423 in inflammatory bowel disease and other indications, and the size of the associated market and patient population opportunities; and Caldera’s clinical development plans, strategy and timelines; as well as any assumptions underlying any of the foregoing. The words “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “expect,” and similar expressions are intended to identify forward-looking statements. These forward-looking statements are subject to risks, uncertainties, and assumptions.
Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, risks and uncertainties related to: (i) the ability to obtain the requisite approval from stockholders of Synlogic and Caldera; (ii) the risk that the proposed transaction may not be completed in a timely manner or at all; (iii) the possibility that competing offers or acquisition proposals will be made; (iv) the possibility that any or all of the various conditions to the consummation of the proposed transaction may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities; (v) the occurrence of any event, change or other circumstance that could give rise to the termination of the merger agreement, including in circumstances that would require either party to pay a termination fee or other expenses; (vi) the effect of the pendency of the proposed transaction on the parties’ ability to retain and hire key personnel, their ability to maintain relationships with customers, suppliers and others with whom they do business, their business generally or their stock price; (vii) risks related to diverting management’s attention from ongoing business operations or the loss of one or more members of the management team; (viii) the risk that stockholder litigation in connection with the proposed transaction may result in significant costs of defense, indemnification and liability; (ix) the parties’ ability to realize the anticipated benefits of the proposed transaction; (x) the risk that the parties may assume unexpected liabilities and expenses as a result of the transaction; (xi) uncertainties as to Caldera’s anticipated preclinical and clinical drug development activities and related timelines, including the expected timing for commencing clinical trials and announcing data and other clinical results; (xii) the risk that interim, preliminary or topline clinical data may change as additional data become available, and that early clinical results may not be predictive of results in later-stage clinical trials or in patients; and (xiii) uncertainties regarding the safety, efficacy,
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immunogenicity, pharmacokinetic profile and regulatory path of CLD-423, including interactions with and approvals from applicable regulatory authorities. For information regarding other related risks, see the “Risk Factors” section of Synlogic’s Annual Report on Form 10-K for the year ended December 31, 2025, filed with the SEC on March 12, 2026, as amended on April 30, 2026, Synlogic’s most recent Quarterly Report on Form 10-Q and Synlogic’s other filings with the SEC. Should any of these risks or uncertainties materialize, actual results could differ materially from expectations. These forward-looking statements speak only as of the date hereof. Neither Synlogic nor Caldera assumes any obligation to, and does not currently intend to, update any such forward-looking statements except as may be required by law.
For Caldera Therapeutics Inquiries:
Lauren Arnold
LA Communications
Lauren@LaCommunications.net
For Synlogic Inquiries:
info@synlogictx.com
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