Amendment: SEC Form SCHEDULE 13D/A filed by Larimar Therapeutics Inc.

Item 3 of the Schedule 13D is hereby amended by adding the following: On February 27, 2026, Deerfield Private Design Fund III, Deerfield Private Design Fund IV, Deerfield Healthcare Innovations Fund and Deerfield Partners purchased 1,084,010, 1,084,012, 831,978 and 2,000,000 shares of Common Stock (collectively, the "February 2026 Shares"), respectively, at a price of $5.00 per share, or aggregate purchase prices of $5,420,050, $5,420,060, $4,159,890 and $10,000,000, respectively. Each Fund utilized available cash assets to acquire the February 2026 Shares.

Item 4 of the Schedule 13D is hereby amended by adding the following: Each Fund acquired its February 2026 Shares for investment purposes in an underwritten offering conducted by the Company (the "February 2026 Offering") pursuant to the Prospectus Supplement, dated as of February 25, 2026, to the Issuer's Prospectus, dated as of May 24, 2024 (the "February 2026 Offering").

Items 5(a), 5(b) and 5(c) of the Schedule 13D are hereby amended and restated in their entirety to read as follows: (1) Deerfield Private Design Fund III Number of shares: 10,622,928 Percentage of shares: 10.25%* (2) Deerfield Healthcare Innovations Fund Number of shares: 8,153,107 Percentage of shares: 7.87%* (3) Deerfield Private Design Fund IV Number of shares: 10,622,957 Percentage of shares: 10.25%* (4) Deerfield Partners Number of shares: 6,207,982 Percentage of shares: 5.99%* (5) Deerfield Mgmt III Number of shares: 10,622,928 (comprised of shares held by Deerfield Private Design Fund III) Percentage of shares: 10.25%* (6) Deerfield Mgmt HIF Number of shares: 8,153,107 (comprised of shares held by Deerfield Healthcare Innovations Fund) Percentage of shares: 7.87%* (7) Deerfield Mgmt IV Number of shares: 10,622,957 (comprised of shares held by Deerfield Private Design Fund) Percentage of shares: 10.25%* (8) Deerfield Mgmt Number of shares: 6,207,982 (comprised of shares held by Deerfield Partners) Percentage of shares: 5.99%* (9) Deerfield Management Number of shares: 35,667,474 (comprised of shares held by Deerfield Private Design Fund III, Deerfield Private Design Fund IV, Deerfield Healthcare Innovations Fund, Deerfield Partners and shares underlying options held by Jonathan Leff at the direction and for the benefit of Deerfield Management) Percentage of shares: 34.41%* (10) James E. Flynn Number of shares: 35,667,474 (comprised of shares held by Deerfield Private Design Fund III, Deerfield Private Design Fund IV, Deerfield Healthcare Innovations Fund, Deerfield Partners and shares underlying options held by Jonathan Leff at the direction and for the benefit of Deerfield Management) Percentage of shares: 34.41%* * Throughout this report, the percentage of outstanding Common Stock beneficially owned by the Reporting Persons reflects 103,590,392 shares of Common Stock outstanding, including shares issued in the February 2026 Offering, based on information set forth in the Prospectus Supplement, dated as of February 25, 2026, filed by the Company with the Securities and Exchange Commission on February 26, 2026.

Items 5(a), 5(b) and 5(c) of the Schedule 13D are hereby amended and restated in their entirety to read as follows: (1) Deerfield Private Design Fund III Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 10,622,928 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 10,622,928 (2) Deerfield Healthcare Innovations Fund Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 8,153,107 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 8,153,107 (3) Deerfield Private Design Fund IV Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 10,622,957 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 10,622,957 (4) Deerfield Partners Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 6,207,982 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 6,207,982 (5) Deerfield Mgmt III Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 10,622,928 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 10,622,928 (6) Deerfield Mgmt HIF Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 8,153,107 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 8,153,107 (7) Deerfield Mgmt IV Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 10,622,957 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 10,622,957 (8) Deerfield Mgmt Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 6,207,982 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 6,207,982 (9) Deerfield Management Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 35,667,474 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 35,667,474 (10) James E. Flynn Sole power to vote or direct the vote: 0 Shared power to vote or direct the vote: 35,667,474 Sole power to dispose or to direct the disposition: 0 Shared power to dispose or direct the disposition: 35,667,474 James E. Flynn is the sole manager of the general partner of each of Deerfield Mgmt III, Deerfield Mgmt IV, Deerfield Mgmt HIF, Deerfield Mgmt, and Deerfield Management. Deerfield Mgmt III is the general partner of Deerfield Private Design Fund III. Deerfield Mgmt HIF is the general partner of Deerfield Healthcare Innovations Fund. Deerfield Mgmt IV is the general partner of Deerfield Private Design Fund IV. Deerfield Mgmt is the general partner of Deerfield Partners. Deerfield Management is the investment manager of each of Deerfield Private Design Fund III, Deerfield Healthcare Innovations Fund, Deerfield Private Design Fund IV and Deerfield Partners.

Items 5(a), 5(b) and 5(c) of the Schedule 13D are hereby amended and restated in their entirety to read as follows: Except as set forth in Item 3 of this Schedule 13D, no Reporting Person has effected any transactions in the Common Stock during the past 60 days.