# EDGAR Filing Document

**Accession Number:** 0001352546
**File Stem:** 0001193805-26-000206
**Filing Date:** 2026-3
**Character Count:** 35464
**Document Hash:** 61b9281479dad0bfea9f9ca7b6201324
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193805-26-000206.hdr.sgml**: 20260302

**ACCESSION NUMBER**: 0001193805-26-000206

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260302

**DATE AS OF CHANGE**: 20260302

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Larimar Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001374690
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 203857670
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-88225
- **FILM NUMBER:** 26710460

**BUSINESS ADDRESS:**
- **STREET 1:** THREE BALA PLAZA EAST. SUITE 506
- **CITY:** BALA CYNWYD
- **STATE:** PA
- **ZIP:** 19004
- **BUSINESS PHONE:** 844-511-9056

**MAIL ADDRESS:**
- **STREET 1:** THREE BALA PLAZA EAST. SUITE 506
- **CITY:** BALA CYNWYD
- **STATE:** PA
- **ZIP:** 19004

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ZAFGEN, INC.
- **DATE OF NAME CHANGE:** 20100301

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ZAFGEN INC
- **DATE OF NAME CHANGE:** 20060906
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Flynn James E
- **CENTRAL INDEX KEY:** 0001352546

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**MAIL ADDRESS:**
- **STREET 1:** 780 THIRD AVENUE
- **STREET 2:** 37TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10017

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 11)**

**Larimar Therapeutics, Inc.**

*(Name of Issuer)*

**Common Stock, par value $0.01 per share**

*(Title of Class of Securities)*

**517125100**

*(CUSIP Number)*

**Deerfield Management Company**<br>345 Park Avenue, 12th Floor<br>New York NY 10010<br>212-551-1600

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

**02/27/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Private Design Fund III, L.P.** | Name of reporting person<br>**Deerfield Private Design Fund III, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**10622928.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**10622928.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10622928.00** | Aggregate amount beneficially owned by each reporting person<br>**10622928.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**10.25%** | Percent of class represented by amount in Row (11)<br>**10.25%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Healthcare Innovations Fund, L.P.** | Name of reporting person<br>**Deerfield Healthcare Innovations Fund, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**8153107.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**8153107.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**8153107.00** | Aggregate amount beneficially owned by each reporting person<br>**8153107.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**7.87%** | Percent of class represented by amount in Row (11)<br>**7.87%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Private Design Fund IV, L.P.** | Name of reporting person<br>**Deerfield Private Design Fund IV, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**10622957.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**10622957.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10622957.00** | Aggregate amount beneficially owned by each reporting person<br>**10622957.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**10.25%** | Percent of class represented by amount in Row (11)<br>**10.25%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Partners, L.P.** | Name of reporting person<br>**Deerfield Partners, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**6207982.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**6207982.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**6207982.00** | Aggregate amount beneficially owned by each reporting person<br>**6207982.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.99%** | Percent of class represented by amount in Row (11)<br>**5.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Mgmt III, L.P.** | Name of reporting person<br>**Deerfield Mgmt III, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**10622928.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**10622928.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10622928.00** | Aggregate amount beneficially owned by each reporting person<br>**10622928.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**10.25%** | Percent of class represented by amount in Row (11)<br>**10.25%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** Comprised of shares of common stock held by Deerfield Private Design Fund III, L.P., of which Deerfield Mgmt III, L.P. is the general partner.

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Mgmt HIF, L.P.** | Name of reporting person<br>**Deerfield Mgmt HIF, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**8153107.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**8153107.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**8153107.00** | Aggregate amount beneficially owned by each reporting person<br>**8153107.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**7.87%** | Percent of class represented by amount in Row (11)<br>**7.87%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** Comprised of shares of common stock held by Deerfield Healthcare Innovations Fund, L.P., of which Deerfield Mgmt HIF, L.P. is the general partner.

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Mgmt IV, L.P.** | Name of reporting person<br>**Deerfield Mgmt IV, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**10622957.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**10622957.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10622957.00** | Aggregate amount beneficially owned by each reporting person<br>**10622957.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**10.25%** | Percent of class represented by amount in Row (11)<br>**10.25%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** Comprised of shares of common stock held by Deerfield Private Design Fund IV, L.P., of which Deerfield Mgmt IV, L.P. is the general partner.

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Mgmt, L.P.** | Name of reporting person<br>**Deerfield Mgmt, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**6207982.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**6207982.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**6207982.00** | Aggregate amount beneficially owned by each reporting person<br>**6207982.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.99%** | Percent of class represented by amount in Row (11)<br>**5.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** Comprised of shares of common stock held by Deerfield Partners, L.P., of which Deerfield Mgmt, L.P. is the general partner.

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Deerfield Management Company, L.P.** | Name of reporting person<br>**Deerfield Management Company, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**35667474.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**35667474.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**35667474.00** | Aggregate amount beneficially owned by each reporting person<br>**35667474.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**34.41%** | Percent of class represented by amount in Row (11)<br>**34.41%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** Comprised of (i) an aggregate of 35,606,974 shares of common stock held by Deerfield Private Design Fund III, L.P., Deerfield Private Design Fund IV, L.P., Deerfield Healthcare Innovations Fund, L.P. and Deerfield Partners, L.P., of which Deerfield Management Company, L.P. is the investment manager and (ii) an aggregate of 60,500 shares of common stock issuable upon exercise of options (the "Leff Options") held by Jonathan Leff, an employee of Deerfield Management Company, L.P., for the benefit, and subject to the direction, of Deerfield Management Company, L.P.  The Leff Options consist options that were granted to Mr. Leff on July 16, 2020, May 12, 2021, May 10, 2022, May 9, 2023 and May 29, 2024, each of which is fully vested.

| **CUSIP No.** | **517125100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**James E. Flynn** | Name of reporting person<br>**James E. Flynn** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**35667474.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**35667474.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**35667474.00** | Aggregate amount beneficially owned by each reporting person<br>**35667474.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**34.41%** | Percent of class represented by amount in Row (11)<br>**34.41%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** Comprised of (i) an aggregate of 35,606,974 shares of common stock held by Deerfield Private Design Fund III, L.P., Deerfield Private Design Fund IV, L.P., Deerfield Healthcare Innovations Fund, L.P. and Deerfield Partners, L.P., of which Deerfield Management Company, L.P. is the investment manager and (ii) an aggregate of 60,500 shares of common stock issuable upon exercise of options (the "Leff Options") held by Jonathan Leff, an employee of Deerfield Management Company, L.P., for the benefit, and subject to the direction, of Deerfield Management Company, L.P.  The Leff Options consist options that were granted to Mr. Leff on July 16, 2020, May 12, 2021, May 10, 2022, May 9, 2023 and May 29, 2024, each of which is fully vested.  Mr. Flynn is the sole manager of the general partner of each of Deerfield Mgmt III, L.P., Deerfield Mgmt IV, L.P., Deerfield Mgmt HIF, L.P., Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.01 per share

**(b) Name of Issuer:**
Larimar Therapeutics, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
THREE BALA PLAZA EAST, SUITE 506, BALA CYNWYD, PA, 19004

This Amendment No. 11 (this "Amendment") to Schedule 13D is filed by (i) Deerfield Private Design Fund III, L.P. ("Deerfield Private Design Fund III"), (ii) Deerfield Healthcare Innovations Fund, L.P. ("Deerfield Healthcare Innovations Fund"), (iii) Deerfield Private Design Fund IV, L.P. ("Deerfield Private Design Fund IV"), (iv) Deerfield Partners, L.P. ("Deerfield Partners"), (v) Deerfield Mgmt III, L.P. ("Deerfield Mgmt III"), (vi) Deerfield Mgmt HIF, L.P. ("Deerfield Mgmt HIF"), (vii) Deerfield Mgmt IV, L.P. ("Deerfield Mgmt IV"), (viii) Deerfield Mgmt, L.P. ("Deerfield Mgmt"), (ix) Deerfield Management Company, L.P. ("Deerfield Management") and (x) James E. Flynn ("Flynn" and, together with Deerfield Private Design Fund III, Deerfield Healthcare Innovations Fund, Deerfield Private Design Fund IV, Deerfield Partners, Deerfield Mgmt III, Deerfield Mgmt HIF, Deerfield Mgmt IV, Deerfield Mgmt and Deerfield Management, the "Reporting Persons"), with respect to the securities of Larimar Therapeutics, Inc. (as amended by Amendment No.1, Amendment No. 2, Amendment No. 3, Amendment No. 4, Amendment No. 5, Amendment No. 6, Amendment No. 7, Amendment No. 8, Amendment No. 9, Amendment No. 10 and this Amendment No. 11, the "Schedule 13D"). Deerfield Private Design Fund III, Deerfield Healthcare Innovations Fund, Deerfield Private Design Fund IV and Deerfield Partners are collectively referred to herein as the "Funds".

Capitalized terms used herein but not otherwise defined herein shall have the meanings ascribed to them in the Schedule 13D.

**Item 4. Purpose of Transaction**

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").

**Item 5. Interest in Securities of the Issuer**

**(a)**
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.

**(b)**
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.

**(c)**
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.

### SIGNATURE

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

**Reporting Person:** Deerfield Private Design Fund III, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Healthcare Innovations Fund, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Private Design Fund IV, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Partners, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Mgmt III, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Mgmt HIF, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Mgmt IV, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Mgmt, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** Deerfield Management Company, L.P.

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026

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

**Reporting Person:** James E. Flynn

**Signature:** /s/ Jonathan Isler

**Name/Title:** Jonathan Isler, Attorney-in-Fact

**Date:** 03/02/2026