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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549 |
SCHEDULE 13D
Under the Securities Exchange Act of 1934
(Amendment No. 8)*
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SPYRE THERAPEUTICS, INC. (Name of Issuer) |
Common Stock, $0.0001 par value (Title of Class of Securities) |
(CUSIP Number) |
Ms. Erin O'Connor Fairmount Funds Management LLC, 200 Barr Harbor Drive, Suite 400 West Conshohocken, PA, 19428 (267) 262-5300 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) |
10/07/2026 (Date of Event Which Requires Filing of This Statement) |

SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Fairmount Funds Management LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b)
| ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
9,354,200.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
![]() | ||||||||
| 13 | Percent of class represented by amount in Row (11)
9.19 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IA |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Fairmount Healthcare Fund II L.P. | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b)
| ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
![]() | ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
9,354,200.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
![]() | ||||||||
| 13 | Percent of class represented by amount in Row (11)
9.19 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Harwin Peter Evan | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b)
| ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
UNITED STATES
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
10,185,961.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
![]() | ||||||||
| 13 | Percent of class represented by amount in Row (11)
9.99 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Kiselak Tomas | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b)
| ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
SLOVAKIA
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
10,185,961.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
![]() | ||||||||
| 13 | Percent of class represented by amount in Row (11)
9.99 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13D
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| 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,
MASSACHUSETTS
, 02453. | |
Item 1 Comment:
This Amendment No. 8 amends and supplements the statement on Schedule 13D originally filed with
the 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, and Amendment No. 7 filed on June 23, 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. This Amendment No. 8 is being filed solely to report the Reporting Persons' entry into a lock-agreement in connection with the Company's underwritten public offering; the number of shares of Common Stock and Series A Preferred Stock beneficially owned by the Reporting Persons has not changed since Amendment No. 7 to the Statement, filed on June 23, 2026. | ||
| 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. 8 is incorporated by reference herein.
Together, the Reporting Persons' securities include (i) 812,076 shares of Common Stock owned by the Reporting Persons, (ii) 9,100,160 shares of Common Stock issuable upon conversion of 227,504 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 (iii) 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 4,741,640 shares of Common Stock issuable upon conversion of 118,541 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. 8 is incorporated by reference herein. | |
| Item 6. | Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer | |
Lock-Up Agreement
In connection with the Company's underwritten public offering of common stock that closed on October 7, 2026, the Reporting Persons entered into a customary lock-up letter agreement (the "Lock-Up Agreement") with Jefferies LLC, TD Securities (USA) LLC, Leerink Partners LLC and Stifel, Nicolaus & Company, Incorporated, acting as the representatives of the underwriters (collectively, the "Representatives") to an underwriting agreement with the Company. Pursuant to the Lock-Up Agreement, the Reporting Persons agreed to refrain from selling shares of the Company's securities without the consent of the Representatives, and other customary lock-up conditions, for a period of 60 days following the date of the final prospectus supplement for the offering.
The Reporting Persons did not purchase any securities of the Company or otherwise participate in the offering.
The foregoing description of the Lock-Up Agreement does not purport to be complete and is qualified in its entirety by reference to the Form of Lock-Up Agreement, which is filed as Exhibit 99.2 to this Schedule 13D and incorporated herein by reference. | ||
| Item 7. | Material to be Filed as Exhibits. | |
99.1 Joint Filing Agreement 99.1 (incorporated by reference to Exhibit 99.1 of the Reporting Persons' Schedule 13D filed with the SEC on October 17, 2025).
99.2 Lock-Up Agreement (incorporated by reference to Exhibit A to the Underwriting Agreement filed as Exhibit 1.1 of the Company's Form 8-K filed with the SEC on October 7, 2026). | ||
| 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.
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