CBIO · Crescent Biopharma, Inc.

The Pre-Funded Warrants have no expiration date and are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of outstanding shares of common stock of the Issuer immediately after giving effect to such exercise.

Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025 and March 17, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the reporting person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 26, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025 and March 17, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the reporting person on February 28, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.88 to $18.86, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

This option represents a right to purchase 11,050 of the Issuer's ordinary shares and vests in full on the earlier of (i) June 2, 2027 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase 11,050 of the Issuer's ordinary shares and vests in full on the earlier of (i) June 2, 2027 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase 11,050 of the Issuer's ordinary shares and vests in full on the earlier of (i) June 2, 2027 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase 11,050 of the Issuer's ordinary shares and vests in full on the earlier of (i) June 2, 2027 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II LP ("Fund II"). Peter Harwin and Tomas Kiselak are the managers of Fairmount. Under Mr. Harwin's arrangement with Fairmount, Mr. Harwin holds the option for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Harwin is obligated to turn over to Fairmount any net cash or stock received from the option for the benefit of such Fairmount Fund. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

This option represents a right to purchase 11,050 of the Issuer's ordinary shares and vests in full on the earlier of (i) June 2, 2027 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This Option represents a right to purchase shares of the Issuer's Ordinary Shares and vests with respect to 1/48th of the Option on each monthly anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

Represents an award of Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Ordinary Shares. The RSUs shall vest in approximately equal three-month installments through the four-year anniversary of December 15, 2025, subject to the Reporting Person remaining continuously employed by or providing services to the Issuer or its subsidiaries from December 15, 2025 through each such vesting date.

This option represents a right to purchase shares of the Issuer's ordinary shares and vests in 48 approximately equal monthly installments that commenced on December 8, 2025.

This option represents a right to purchase shares of the Issuer's ordinary shares and vests in 48 approximately equal monthly installments that commenced on December 8, 2025.

The Pre-Funded Warrants have no expiration date and are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of outstanding shares of common stock of the Issuer immediately after giving effect to such exercise.

Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

This option will vest as to 25% on July 7, 2026 and in equal monthly installments thereafter through July 7, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

This option represents a right to purchase shares of the Issuer's ordinary shares and vests in full on the earlier of (i) June 23, 2026 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase shares of the Issuer's ordinary shares and vests in full on the earlier of (i) June 23, 2026 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase 9,023 of the Issuer's ordinary shares, which vest in full on the earlier of (i) June 23, 2026 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

Under Mr. Harwin's arrangement with Fairmount Funds Management LLC ("Fairmount"), Mr. Harwin holds the option for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Harwin is obligated to turn over to Fairmount any net cash or shares received from the option for the benefit of such Fairmount Fund. Mr. Harwin therefore disclaims beneficial ownership of the option and underlying ordinary shares. Fairmount disclaims beneficial ownership of any of the reported securities, except to the extent of its pecuniary interest therein.

This option represents a right to purchase shares of the Issuer's ordinary shares and vests in full on the earlier of (i) June 23, 2026 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This option represents a right to purchase shares of the Issuer's ordinary shares and vests in full on the earlier of (i) June 23, 2026 or (ii) the date of the Issuer's next annual meeting of shareholders, in each case, subject to the Reporting Person's continued service to the Issuer.

This Form 4 is filed jointly by Biotechnology Value Fund, L.P. ("BVF"), Biotechnology Value Fund II, L.P. ("BVF2"), Biotechnology Value Trading Fund OS LP ("Trading Fund OS"), BVF Partners OS Ltd. ("Partners OS"), BVF I GP LLC ("BVF GP"), BVF II GP LLC ("BVF2 GP"), BVF GP Holdings LLC ("BVF GPH"), BVF Partners L.P. ("Partners"), BVF Inc. and Mark N. Lampert (collectively, the "Reporting Persons"). Each of the Reporting Persons is a member of a Section 13(d) group that previously collectively owned more than 10% of the Issuer's outstanding shares of Common Stock (the "Common Stock"). Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein except to the extent of his or its pecuniary interest therein.

On June 13, 2025, the Issuer completed a reverse merger transaction (the "Merger") with Crescent Biopharma, Inc. pursuant to that certain Agreement and Plan of Merger and Reorganization, dated October 28, 2024, as amended by Amendment No. 1 to the Agreement and Plan of Merger and Reorganization, dated February 14, 2025. In connection with the Merger, the Reporting Persons acquired an aggregate of 1,292,422 shares of Common Stock and 597,928 pre-funded warrants to purchase shares of Common Stock (the "Pre-Funded Warrants"), in exchange for all of the former Crescent Biopharma, Inc. capital stock owned by the Reporting Persons.

Represents the number of securities owned following the Issuer's 1-for-100 Reverse Stock Split effected immediately prior to the Merger.

Securities owned directly by BVF2. As the general partner of BVF2, BVF2 GP may be deemed to beneficially own the securities owned directly by BVF2. As the sole member of BVF2 GP, BVF GPH may be deemed to beneficially own the securities owned directly by BVF2. As the investment manager of BVF2, Partners may be deemed to beneficially own the securities owned directly by BVF2. As the investment adviser and general partner of Partners, BVF Inc. may be deemed to beneficially own the securities owned directly by BVF2. As a director and officer of BVF Inc., Mr. Lampert may be deemed to beneficially own the securities owned directly by BVF2.