# EDGAR Filing Document

**Accession Number:** 0001802528
**File Stem:** 0001104659-26-076961
**Filing Date:** 2026-6
**Character Count:** 20089
**Document Hash:** e2bdb9f193de2157656987d722602729
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-076961.hdr.sgml**: 20260623

**ACCESSION NUMBER**: 0001104659-26-076961

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

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260623

**DATE AS OF CHANGE**: 20260623

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Spyre Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001636282
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 464312787
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-89456
- **FILM NUMBER:** 261112852

**BUSINESS ADDRESS:**
- **STREET 1:** 221 CRESCENT STREET
- **STREET 2:** BUILDING 23, SUITE 105
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453
- **BUSINESS PHONE:** 6176515940

**MAIL ADDRESS:**
- **STREET 1:** 221 CRESCENT STREET
- **STREET 2:** BUILDING 23, SUITE 105
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Aeglea BioTherapeutics, Inc.
- **DATE OF NAME CHANGE:** 20150311
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Fairmount Funds Management LLC
- **CENTRAL INDEX KEY:** 0001802528

**ORGANIZATION NAME:**
- **EIN:** 364841215
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

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

**BUSINESS ADDRESS:**
- **STREET 1:** 200 BARR HARBOR DRIVE
- **STREET 2:** SUITE 400
- **CITY:** WEST CONSHOHOCKEN
- **STATE:** PA
- **ZIP:** 19428
- **BUSINESS PHONE:** 267-262-5300

**MAIL ADDRESS:**
- **STREET 1:** 200 BARR HARBOR DRIVE
- **STREET 2:** SUITE 400
- **CITY:** WEST CONSHOHOCKEN
- **STATE:** PA
- **ZIP:** 19428

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 7)**

**SPYRE THERAPEUTICS, INC.**

*(Name of Issuer)*

**Common Stock, $0.0001 par value**

*(Title of Class of Securities)*

**—**

*(CUSIP Number)*

**Ms. Erin O'Connor**<br>Fairmount Funds Management LLC<br>200 Barr Harbor Drive, Suite 400<br>West Conshohocken PA 19428<br>(267) 262-5300

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

**06/23/2026**

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

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Fairmount Funds Management LLC** | Name of reporting person<br>**Fairmount Funds Management LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (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>**8835440.00** |
| 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>**8835440.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**8835440.00** | Aggregate amount beneficially owned by each reporting person<br>**8835440.00** | |
| 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>**9.15%** | Percent of class represented by amount in Row (11)<br>**9.15%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

**Comment for Reporting Person:** The securities represent 8,835,440 shares of common stock, $0.0001 par value per share (the "Common Stock") issuable upon conversion of 220,886 shares of Series A Preferred Stock, par value $0.0001 per share (the "Series A Preferred Stock"), held directly by Fairmount Healthcare Fund II L.P. ("Fund II"). The securities exclude shares of Common Stock issuable upon conversion of shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.99%.

Row 13 is based on 96,572,019 shares of Common Stock outstanding as of June 23, 2026, consisting of (i) 86,841,253 shares of Common Stock outstanding as of April 28, 2026, as reported in the Company's Form 10-Q filed on May 5, 2026, (ii) 666,680 shares of Common Stock issued upon the June 23, 2026 conversion by Fund II of 16,667 shares of the Series B Preferred Stock, par value $0.0001 per share (the "Series B Preferred Stock") (iii) 228,646 shares underlying options that are currently exercisable or will be exercisable within 60 days of the date of this filing by the Reporting Persons and (iv) 8,835,440 shares of Common Stock underlying the 220,886 shares of Series A Preferred Stock owned by Fund II, applying the beneficial ownership limitation.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Fairmount Healthcare Fund II L.P.** | Name of reporting person<br>**Fairmount Healthcare Fund II L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (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>**8835440.00** |
| 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>**8835440.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**8835440.00** | Aggregate amount beneficially owned by each reporting person<br>**8835440.00** | |
| 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>**9.15%** | Percent of class represented by amount in Row (11)<br>**9.15%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** The securities represent 8,835,440 shares of Common Stock issuable upon conversion of 220,886 shares of Series A Preferred Stock held directly by Fund II. The securities exclude shares of Common Stock issuable upon conversion of shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.99%.

Row 13 is based on 96,572,019 shares of Common Stock outstanding as of June 23, 2026, consisting of (i) 86,841,253 shares of Common Stock outstanding as of April 28, 2026, as reported in the Company's Form 10-Q filed on May 5, 2026, (ii) 666,680 shares of Common Stock issued upon the June 23, 2026 conversion by Fund II of 16,667 shares of the Series B Preferred Stock (iii) 228,646 shares underlying options that are currently exercisable or will be exercisable within 60 days of the date of this filing by the Reporting Persons and (iv) 8,835,440 shares of Common Stock underlying the 220,886 shares of Series A Preferred Stock owned by Fund II, applying the beneficial ownership limitation.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Peter Evan Harwin** | Name of reporting person<br>**Peter Evan Harwin** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (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>**520361.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**9146840.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**520361.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**9146840.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**9667201.00** | Aggregate amount beneficially owned by each reporting person<br>**9667201.00** | |
| 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>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** The securities include (a) 406,038 shares of Common Stock held directly by Mr. Harwin, (b) 114,323 shares of Common Stock issuable upon the exercise of options that are currently exercisable or will be exercisable within 60 days of the date of this filing held directly by Mr. Harwin*, and (c) Fund II's direct holdings of 9,146,840 shares of Common Stock issuable upon conversion of 228,671 shares of Series A Preferred Stock held directly by Fund II. The securities exclude shares of Common Stock issuable upon conversion of shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.99%.

Row 13 is based on 96,769,096 shares of Common Stock outstanding as of June 23, 2026, consisting of (i) 86,841,253 shares of Common Stock outstanding as of April 28, 2026, as reported in the Company's Form 10-Q filed on May 5, 2026, (ii) 666,680 shares of Common Stock issued upon the June 23, 2026 conversion by Fund II of 16,667 shares of the Series B Preferred Stock, (iii) 114,323 shares of Common Stock underlying options that are currently exercisable or will be exercisable within 60 days of the date of this filing by Mr. Harwin and (iii) 9,146,840 shares of Common Stock underlying the 228,671 shares of Series A Preferred Stock owned by Fund II, applying the beneficial ownership limitation.

* Under Mr. Harwin's arrangement with Fairmount, Mr. Harwin holds the options 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. Mr. Harwin therefore disclaims beneficial ownership of the option and underlying common stock.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Tomas Kiselak** | Name of reporting person<br>**Tomas Kiselak** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (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>**2B** | Citizenship or place of organization<br>**2B** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**520361.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**9146840.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**520361.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**9146840.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**9667201.00** | Aggregate amount beneficially owned by each reporting person<br>**9667201.00** | |
| 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>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** The securities include (a) 406,038 shares of Common Stock held directly by Mr. Kiselak, (b) 114,323 shares of Common Stock issuable upon the exercise of options that are currently exercisable or will be exercisable within 60 days of the date of this filing held directly by Mr. Kiselak*, and (c) Fund II's direct holdings of 9,146,840 shares of Common Stock issuable upon conversion of 228,671 shares of Series A Preferred Stock held directly by Fund II. The securities exclude shares of Common Stock issuable upon conversion of shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.99%.

Row 13 is based on 96,769,096 shares of Common Stock outstanding as of June 23, 2026, consisting of (i) 86,841,253 shares of Common Stock outstanding as of April 28, 2026, as reported in the Company's Form 10-Q filed on May 5, 2026, (ii) 666,680 shares of Common Stock issued upon the June 23, 2026 conversion by Fund II of 16,667 shares of the Series B Preferred Stock, (iii) 114,323 shares of Common Stock underlying options that are currently exercisable or will be exercisable within 60 days of the date of this filing by Mr. Harwin and (iii) 9,146,840 shares of Common Stock underlying the 228,671 shares of Series A Preferred Stock owned by Fund II, applying the beneficial ownership limitation.

* Under Mr. Kiselak's arrangement with Fairmount, Mr. Kiselak holds the options for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Kiselak is obligated to turn over to Fairmount any net cash or stock received from the option for the benefit of such Fairmount Fund. Mr. Kiselak therefore disclaims beneficial ownership of the option and underlying common stock.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, $0.0001 par value

**(b) Name of Issuer:**
SPYRE THERAPEUTICS, INC.

**(c) Address of Issuer's Principal Executive Offices:**
221 Crescent Street, Building 23, Suite 105, Waltham, MA, 02453

This Amendment No. 7 amends and supplements the statement on Schedule 13D originally filed withthe Securities and Exchange Commission (the "SEC") on June 30, 2023, Amendment No. 1 filed on November 29, 2023, Amendment No. 2 filed on December 11, 2023, Amendment No. 3 filed on December 29, 2023, Amendment No. 4 filed on April 25, 2024, Amendment No. 5 filed on October 17, 2025, and Amendment No. 6 filed on April 20, 2026 (as amended, the "Statement" or the "Schedule 13D") by the Reporting Persons with respect to the Common Stock of the Company. Unless otherwise defined herein, capitalized terms used in this Amendment No. 7 shall have the meanings ascribed to them in the Statement. Unless amended or supplemented below, the information in the Statement remains unchanged.

**Item 4. Purpose of Transaction**

Item 4 of the Schedule 13D is hereby amended and supplemented as follows:

Resignation of Peter Harwin

On May 27, 2026, Peter Harwin resigned from the Board of Directors of the Company. Mr. Harwin's resignation was not the result of any disagreement with the Company on any matter relating to the Company's operations, policies or practices.

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

**(a)**
The information in rows 11 and 13 of each of the cover pages (including the explanatory note in the "Comments") of this Amendment No. 7 is incorporated by reference herein.

Together, the Reporting Persons' securities include (i) 8,581,440 shares of Common Stock issuable upon conversion of 214,536 shares of Series A Preferred Stock subject to the 9.99% beneficial ownership limitation applied to all of the securities owned by the Reporting Persons and (ii) 228,646 shares of Common Stock issuable upon the exercise of options held by the Reporting Persons that are currently exercisable or will be exercisable within 60 days of the date of this filing. The securities exclude 5,260,360 shares of Common Stock issuable upon conversion of 131,509 shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.99%.

**(b)**
The information in rows 7 through 10 of each of the cover pages of this Amendment No. 7 is incorporated by reference herein.

**(c)**
Item 5(c) of the Schedule 13D is hereby supplemented as follows:

On June 23, 2026, Fund II sold in a block trade a total of 4,684,781 shares of Common Stock at a price of $85.31 per share.

### 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:** Fairmount Funds Management LLC

**Signature:** /s/ Peter Harwin

**Name/Title:** Peter Harwin, Managing Member

**Date:** 06/23/2026

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:** Fairmount Healthcare Fund II L.P.

**Signature:** /s/ Peter Harwin

**Name/Title:** Peter Harwin, Managing Member

**Date:** 06/23/2026

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:** Peter Evan Harwin

**Signature:** /s/ Peter Harwin

**Name/Title:** Peter Harwin

**Date:** 06/23/2026

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:** Tomas Kiselak

**Signature:** /s/ Tomas Kiselak

**Name/Title:** Tomas Kiselak

**Date:** 06/23/2026