Fairmount updates Oruka stake, signs 45-day lock-up

Fairmount-affiliated funds filed Amendment No. 5 to their Schedule 13D on Oruka Therapeutics, Inc. to disclose a new lock-up agreement while keeping their reported ownership unchanged.

Rhea-AI Filing Summary

Fairmount-affiliated funds filed Amendment No. 5 to their Schedule 13D on Oruka Therapeutics, Inc. to disclose a new lock-up agreement while keeping their reported ownership unchanged. Fairmount Funds Management LLC and related entities report beneficial ownership of 13,665,080 shares of common stock, representing 19.99% of Oruka’s common stock based on 68,359,627 shares outstanding as of April 30, 2026.

The position includes common shares and shares issuable upon conversion of Series B non-voting convertible preferred stock, subject to a 19.99% beneficial ownership limitation. Additional 5,297,664 warrant shares and 1,468,331 shares issuable from Series B preferred are excluded because of 9.99% and 19.99% ownership caps.

In connection with Oruka’s underwritten public offering that closed on April 30, 2026, the reporting persons entered into a customary lock-up letter with the underwriters, agreeing not to sell company securities for 45 calendar days from the date of the underwriting agreement, unless Leerink Partners consents. They did not purchase securities or otherwise participate in the offering.

Key Figures

Beneficial ownership: 13,665,080 shares Ownership percentage: 19.99% Fund II holdings: 11,091,772 shares +5 more

8 metrics

Beneficial ownership 13,665,080 shares Fairmount Funds Management LLC, 19.99% of common stock

Ownership percentage 19.99% Fairmount and affiliates’ Oruka common stake

Fund II holdings 11,091,772 shares Fairmount Healthcare Fund II L.P., 16.23% of class

Co-Invest holdings 2,573,308 shares Fairmount Healthcare Co-Invest III L.P., 4.41% of class

Shares outstanding base 68,359,627 shares Common stock outstanding basis for 19.99% calculation, April 30, 2026

Core common outstanding 58,382,309 shares Oruka common stock outstanding as of April 30, 2026

Excluded warrant shares 5,297,664 shares Common issuable upon pre-funded warrants, subject to 9.99% cap

Lock-up term 45 calendar days Duration of sales restriction from underwriting agreement date

Key Terms

beneficial ownership limitation, Pre-Funded Warrants, Series B non-voting convertible preferred stock, lock-up letter agreement, +2 more

6 terms

beneficial ownership limitation financial

"The exercise of the Pre-Funded Warrants is subject to a beneficial ownership limitation of 9.99% of the outstanding Common Stock"

A beneficial ownership limitation is a rule that caps the percentage of a company’s shares an investor can be treated as owning or controlling for voting, regulatory or tax purposes. It matters to investors because it can restrict how many shares a person or group can buy or vote, affect takeover chances, and influence share liquidity and value — like a speed limit that prevents any single driver from taking over the whole road.

Pre-Funded Warrants financial

"exclude (i) 5,297,664 shares of Common Stock issuable upon exercise of Pre-Funded Warrants"

Pre-funded warrants are financial instruments that give investors the right to purchase a company's stock at a set price, but with most or all of the purchase price paid upfront. They function like a coupon or gift card for stock, allowing investors to buy shares later at a fixed price, which can be beneficial if they want to avoid future price increases. This makes them important for investors seeking flexibility and certainty in their investment plans.

Series B non-voting convertible preferred stock financial

"shares of Common Stock issuable upon conversion of 119,518 shares of Series B non-voting convertible preferred stock"

A Series B non-voting convertible preferred stock is a class of company shares that gives holders financial priority—such as fixed dividends and first claim on assets if the company is sold—while not granting voting rights. It can be converted into regular common shares under set conditions, which matters to investors because conversion can increase upside participation but also dilute existing owners; the preference reduces downside risk like a safety buffer.

lock-up letter agreement financial

"the Reporting Persons entered into a customary lock-up letter agreement (the "Lock-Up Agreement")"

underwritten public offering financial

"In connection with the Company's underwritten public offering of common stock that closed on April 30, 2026"

An underwritten public offering is when a company sells new shares of its stock to the public with the help of a financial firm, called an underwriter. The underwriter agrees to buy all the shares upfront, reducing the company's risk, and then sells them to investors. This process helps companies raise money quickly and confidently from a wide range of buyers.

beneficially owned financial

"At such time as Fairmount and its affiliates beneficially own 9.0% or less of the Common Stock"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What ownership stake in Oruka Therapeutics (ORKA) does Fairmount report?

Fairmount-affiliated entities report beneficial ownership of 13,665,080 Oruka common shares, representing 19.99% of the class. This figure includes common stock and shares issuable from Series B preferred, calculated against 68,359,627 shares of common stock outstanding as of April 30, 2026.

Did Fairmount change its Oruka (ORKA) position in this Schedule 13D/A?

No, Amendment No. 5 states the number of Oruka common shares, pre-funded warrants and Series B preferred stock beneficially owned by the reporting persons has not changed since Amendment No. 4. The main update is disclosure of a new lock-up agreement tied to an underwritten offering.

What lock-up restrictions apply to Fairmount’s Oruka (ORKA) holdings?

The reporting persons agreed to a customary lock-up for 45 calendar days from the underwriting agreement date. During this period, they will refrain from selling Oruka securities without consent from Leerink Partners, subject to other standard lock-up conditions negotiated with the underwriting syndicate.

How many Oruka (ORKA) shares are excluded due to ownership limits?

The filing notes 5,297,664 shares issuable upon exercise of pre-funded warrants and 1,468,331 shares issuable from Series B preferred are excluded. These are subject to 9.99% and 19.99% beneficial ownership limitations, so any shares above those caps are not currently counted as beneficially owned.

What is the total Oruka (ORKA) share count used for Fairmount’s 19.99% calculation?

Row 13 calculations are based on 68,359,627 Oruka common shares outstanding as of April 30, 2026. This total reflects 58,382,309 common shares outstanding, 17,500 option shares exercisable within 60 days, and 9,959,818 shares underlying Series B preferred stock held by the reporting persons.

Did Fairmount participate in Oruka’s April 30, 2026 underwritten offering?

The filing states the reporting persons did not purchase any Oruka securities or otherwise participate in the underwritten public offering that closed on April 30, 2026. Their involvement was limited to signing a lock-up agreement with the underwriters for a defined 45-day period.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/04/2026 - 06:00 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 5)

ORUKA THERAPEUTICS, INC.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

687604108

(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)

04/30/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 687604108

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)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 13,665,080.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 13,665,080.00

11

Aggregate amount beneficially owned by each reporting person

13,665,080.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

19.99 %

14

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person:

The securities (a) include (i) 1,131,954 shares of common stock, $0.001 par value per share (the "Common Stock") and 9,959,818 shares of Common Stock issuable upon conversion of 119,518 shares of Series B non-voting convertible preferred stock, par value $0.001 per share (the "Series B Preferred Stock"), directly held by Fairmount Healthcare Fund II L.P., a Delaware limited partnership ("Fund II"), and (ii) 2,573,308 shares of Common Stock directly held by Fairmount Healthcare Co-Invest III L.P., a Delaware limited partnership ("Co-Invest"), and (b) exclude (i) 5,297,664 shares of Common Stock issuable upon exercise of Pre-Funded Warrants and (ii) 1,468,331 shares of Common Stock issuable upon conversion of 17,620 shares of Series B Preferred Stock, in each case directly held by Fund II. The exercise of the Pre-Funded Warrants is subject to a beneficial ownership limitation of 9.99% of the outstanding Common Stock and the conversion of the Series B Preferred Stock is subject to a beneficial ownership limitation of 19.99%. The securities exclude shares of Common Stock issuable upon exercise of Pre-Funded Warrants and conversion of shares of Series B Preferred Stock in excess of such beneficial ownership limitations. At such time as Fairmount Funds Management LLC, a Delaware limited liability company and Securities and Exchange Commission registered investment adviser under the Investment Advisers Act of 1940 ("Fairmount"), and its affiliates beneficially own 9.0% or less of the Common Stock, the beneficial ownership limitation with respect to the Series B Preferred Stock will automatically reduce to 9.99%. Row 13 is based on 68,359,627 shares of Common Stock outstanding as of April 30, 2026, consisting of (i) 58,382,309 shares of Common Stock outstanding as of April 30, 2026, as reported in the Company's final prospectus supplement filed pursuant to Rule 424(b)(5) dated April 28, 2026, (ii) 17,500 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 (iii) the 9,959,818 shares of Common Stock underlying the 119,518 shares of Series B Preferred Stock owned by the Reporting Persons, subject to the beneficial ownership limitation.

SCHEDULE 13D

CUSIP Number(s): 687604108

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:

7	Sole Voting Power 0.00
8	Shared Voting Power 11,091,772.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 11,091,772.00

11

Aggregate amount beneficially owned by each reporting person

11,091,772.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

16.23 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

The securities (a) include 1,131,954 shares of Common Stock and 9,959,818 shares of Common Stock issuable upon conversion of 119,518 shares of Series B Preferred Stock and (b) exclude 5,297,664 shares of Common Stock issuable upon exercise of Pre-Funded Warrants and 1,468,331 shares of Common Stock issuable upon conversion of 17,620 shares of Series B Preferred Stock. The exercise of the Pre-Funded Warrants is subject to a beneficial ownership limitation of 9.99% of the outstanding Common Stock and the conversion of the Series B Preferred Stock is subject to a beneficial ownership limitation of 19.99%. The securities exclude shares of Common Stock issuable upon exercise of Pre-Funded Warrants and conversion of shares of Series B Preferred Stock in excess of such beneficial ownership limitations. At such time as Fairmount and its affiliates beneficially own 9.0% or less of the Common Stock, the beneficial ownership limitation with respect to the Series B Preferred Stock will automatically reduce to 9.99%. Row 13 is based on 68,359,627 shares of Common Stock outstanding as of April 30, 2026, consisting of (i) 58,382,309 shares of Common Stock outstanding as of April 30, 2026, as reported in the Company's final prospectus supplement filed pursuant to Rule 424(b)(5) dated April 28, 2026, (ii) 17,500 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 (iii) the 9,959,818 shares of Common Stock underlying the 119,518 shares of Series B Preferred Stock owned by the Reporting Persons, subject to the respective beneficial ownership limitations.

SCHEDULE 13D

CUSIP Number(s): 687604108

1

Name of reporting person

Fairmount Healthcare Co-Invest III 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:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,573,308.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,573,308.00

11

Aggregate amount beneficially owned by each reporting person

2,573,308.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.41 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

The securities include 2,573,308 shares of Common Stock. Row 13 is based on 58,382,309 shares of Common Stock outstanding as of April 30, 2026, as reported in the Company's final prospectus supplement filed pursuant to Rule 424(b)(5) dated April 28, 2026.

SCHEDULE 13D

CUSIP Number(s): 687604108

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)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 17,500.00
8	Shared Voting Power 13,643,163.00
9	Sole Dispositive Power 17,500.00
10	Shared Dispositive Power 13,643,163.00

11

Aggregate amount beneficially owned by each reporting person

13,660,663.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

19.99 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The securities include (a) 17,500 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*, (b) Fund II's direct holdings of (i) 1,131,954 shares of Common Stock and (ii) 9,937,901 shares of Common Stock issuable upon conversion of 119,255 shares of Series B Preferred Stock held directly by Fund II, and (c) Co-Invest's direct holdings of 2,573,308 shares of Common Stock. The securities exclude (i) 5,297,664 shares of Common Stock issuable upon exercise of Pre-Funded Warrants and (ii) 1,490,248 shares of Common Stock issuable upon conversion of 17,883 shares of Series B Preferred Stock, in each case directly held by Fund II. The exercise of the Pre-Funded Warrants is subject to a beneficial ownership limitation of 9.99% of the outstanding Common Stock and the conversion of the Series B Preferred Stock is subject to a beneficial ownership limitation of 19.99%. At such time as Fairmount and its affiliates beneficially own 9.0% or less of the Common Stock, the beneficial ownership limitation with respect to the Series B Preferred Stock will automatically reduce to 9.99%. Row 13 is based on 68,337,710 shares of Common Stock outstanding as of April 30, 2026, consisting of (i) 58,382,309 shares of Common Stock outstanding as of April 30, 2026, as reported in the Company's final prospectus supplement filed pursuant to Rule 424(b)(5) dated April 28, 2026, (ii) 17,500 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 (iii) the 9,937,901 shares of Common Stock underlying the 119,255 shares of Series B Preferred Stock owned by the Reporting Persons, subject to 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.

SCHEDULE 13D

CUSIP Number(s): 687604108

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)

6

Citizenship or place of organization

SLOVAKIA

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 13,665,080.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 13,665,080.00

11

Aggregate amount beneficially owned by each reporting person

13,665,080.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

19.99 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The information in the "Comments" to the cover page for Fairmount Funds Management LLC above is hereby incorporated by reference.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, $0.001 par value per share
(b)	Name of Issuer: ORUKA THERAPEUTICS, INC.
(c)	Address of Issuer's Principal Executive Offices: 855 Oak Grove Avenue, Suite 100, Menlo Park, CALIFORNIA , 94025.
Item 1 Comment: This Amendment No. 5 amends and supplements the statement on Schedule 13D originally filed with the Securities and Exchange Commission (the "SEC") on September 6, 2024, Amendment No. 1 on September 13, 2024, Amendment No. 2 on November 21, 2024, Amendment No. 3 on March 10, 2025, and Amendment No. 4 on September 19, 2025 (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. 5 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. 5 is being filed solely to report the Reporting Persons' entry into a lock-agreement with the Company in connection with the Company's underwritten public offering; the number of shares of Common Stock, Pre-Funded Warrants, and Series B Preferred Stock beneficially owned by the Reporting Persons has not changed since Amendment No. 4 to the Statement, filed on September 19, 2025.
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. 5 is incorporated by reference herein. In the aggregate, the Reporting Persons' securities include (i) 3,705,262 shares of Common Stock, (ii) 17,500 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, (iii) 9,937,901 shares of Common Stock issuable upon conversion of 119,255 shares of Series B Preferred Stock subject to the 19.99% beneficial ownership limitation applied to all of the securities owned by the Reporting Persons. The securities exclude 5,297,664 shares of Common Stock issuable upon conversion of 5,297,664 shares of Pre-Funded Warrants held directly by Fund II, the exercise of which is subject to a beneficial ownership limitation of 9.99% of the outstanding Common Stock and 1,468,331 shares of Common Stock issuable upon conversion of 17,883 shares of Series B Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 19.99%.
(b)	The information in rows 7 through 10 of each of the cover pages of this Amendment No. 5 is incorporated by reference herein.
(c)	None
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 April 30, 2026, the Reporting Persons entered into a customary lock-up letter agreement (the "Lock-Up Agreement") with Leerink Partners LLC ("Leerink Partners"), TD Securities (USA) LLC, Goldman Sachs & Co. LLC, Stifel, Nicolaus & Company, Incorporated and Guggenheim Securities, LLC as the underwriters 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 Leerink Partners, and other customary lock-up conditions, for a period of 45 calendar days from the date of the Underwriting Agreement related to 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 (incorporated by reference to Exhibit 99.1 of the Reporting Persons' Schedule 13D filed with the SEC on September 6, 2024). 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 April 30, 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.

Fairmount Funds Management LLC

Signature:	/s/ Peter Harwin
Name/Title:	Peter Harwin, Managing Member
Date:	05/04/2026

Signature:	/s/ Tomas Kiselak
Name/Title:	Tomas Kiselak, Managing Member
Date:	05/04/2026

Fairmount Healthcare Fund II L.P.

Signature:	/s/ Peter Harwin
Name/Title:	Peter Harwin, Managing Member
Date:	05/04/2026

Signature:	/s/ Tomas Kiselak
Name/Title:	Tomas Kiselak, Managing Member
Date:	05/04/2026

Fairmount Healthcare Co-Invest III L.P.

Signature:	/s/ Peter Harwin
Name/Title:	Peter Harwin, Managing Member
Date:	05/04/2026

Signature:	/s/ Tomas Kiselak
Name/Title:	Tomas Kiselak, Managing Member
Date:	05/04/2026

Harwin Peter Evan

Signature:	/s/ Peter Harwin
Name/Title:	Peter Harwin
Date:	05/04/2026

Kiselak Tomas

Signature:	/s/ Tomas Kiselak
Name/Title:	Tomas Kiselak
Date:	05/04/2026