Adage reports 2.38% Karyopharm Therapeutics stake in 13G/A filing (KPTI)

Rhea-AI Filing Summary

Adage Capital Management and related principals report a 2.38% stake in Karyopharm Therapeutics Inc. common stock. The Reporting Persons beneficially own 436,736 shares, including 15,414 shares issuable upon exercise of warrants. This percentage is based on 18,310,283 shares outstanding as of December 29, 2025.

They state the holdings are maintained in the ordinary course of business and not for the purpose of changing or influencing control of Karyopharm. All voting and dispositive power over these shares is shared among the Reporting Persons, with no sole voting or dispositive authority reported.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Karyopharm Therapeutics Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

48576U205

(CUSIP Number)

12/31/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 48576U205

1

Names of Reporting Persons

Adage Capital Management, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 436,736.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 436,736.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

436,736.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.38 %

12

Type of Reporting Person (See Instructions)

IA, PN

Comment for Type of Reporting Person: Includes 15,414 shares of Common Stock (as defined in Item 2(a)) issuable upon exercise of warrants.

SCHEDULE 13G

CUSIP No. 48576U205

1

Names of Reporting Persons

Robert Atchinson

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 436,736.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 436,736.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

436,736.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.38 %

12

Type of Reporting Person (See Instructions)

HC, IN

Comment for Type of Reporting Person: Includes 15,414 shares of Common Stock issuable upon exercise of warrants.

SCHEDULE 13G

CUSIP No. 48576U205

1

Names of Reporting Persons

Phillip Gross

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 436,736.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 436,736.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

436,736.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.38 %

12

Type of Reporting Person (See Instructions)

HC, IN

Comment for Type of Reporting Person: Includes 15,414 shares of Common Stock issuable upon exercise of warrants.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Karyopharm Therapeutics Inc.
(b)	Address of issuer's principal executive offices: 85 Wells Avenue, 2nd Floor, Newton, MA 02459
Item 2.
(a)	Name of person filing: This statement is filed by: (i) Adage Capital Management, L.P., a Delaware limited partnership ("ACM"), as the investment manager of Adage Capital Partners, L.P., a Delaware limited partnership ("ACP"), with respect to the shares of common stock, par value $0.0001 per share ("Common Stock") of Karyopharm Therapeutics Inc., a Delaware corporation (the "Company") and shares of Common Stock issuable upon exercise of warrants directly held by ACP; (ii) Robert Atchinson ("Mr. Atchinson"), as (1) managing member of Adage Capital Advisors, L.L.C., a limited liability company organized under the laws of the State of Delaware ("ACA"), managing member of Adage Capital Partners GP, L.L.C., a limited liability company organized under the laws of the State of Delaware ("ACPGP"), general partner of ACP and (2) managing member of Adage Capital Partners LLC, a Delaware limited liability company ("ACPLLC"), general partner of ACM, with respect to the shares of Common Stock and shares of Common Stock issuable upon exercise of warrants directly held by ACP; and (iii) Phillip Gross ("Mr. Gross"), as (1) managing member of ACA, managing member of ACPGP and (2) managing member of ACPLLC, general partner of ACM, with respect to the shares of Common Stock and shares of Common Stock issuable upon exercise of warrants directly held by ACP. The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. The filing of this statement should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of the securities reported herein.
(b)	Address or principal business office or, if none, residence: The address of the business office of each of the Reporting Persons is 200 Clarendon Street, 52nd Floor, Boston, Massachusetts 02116.
(c)	Citizenship: ACM is a limited partnership organized under the laws of the State of Delaware. Messrs. Gross and Atchinson are citizens of the United States.
(d)	Title of class of securities: Common Stock, par value $0.0001 per share
(e)	CUSIP No.: 48576U205
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: The information required by Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in this Schedule 13G is calculated based upon an aggregate of 18,310,283 shares of Common Stock outstanding as of December 29, 2025, as reported in the Company's Preliminary Proxy Statement on Schedule 14A, filed with the Securities and Exchange Commission on December 30, 2025, and assumes the exercise of the warrants held by ACP.
(b)	Percent of class: 2.38%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(ii) Shared power to vote or to direct the vote: The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iii) Sole power to dispose or to direct the disposition of: The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iv) Shared power to dispose or to direct the disposition of: The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. See Item 2(a)
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

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.

Adage Capital Management, L.P.

Signature:	/s/ Robert Atchinson
Name/Title:	By: Adage Capital Partners LLC, its General Partner, By: Robert Atchinson, its Managing Member
Date:	02/12/2026

Robert Atchinson

Signature:	/s/ Robert Atchinson
Name/Title:	Robert Atchinson, individually
Date:	02/12/2026

Phillip Gross

Signature:	/s/ Phillip Gross
Name/Title:	Phillip Gross, individually
Date:	02/12/2026

FAQ

What ownership stake in Karyopharm Therapeutics (KPTI) is reported in this Schedule 13G/A?

The filing reports that the group beneficially owns 2.38% of Karyopharm’s common stock. This corresponds to 436,736 shares, including 15,414 shares issuable upon exercise of warrants, based on 18,310,283 shares outstanding as of December 29, 2025.

Who are the reporting persons in the Karyopharm Therapeutics (KPTI) Schedule 13G/A?

The reporting persons are Adage Capital Management, L.P., and individuals Robert Atchinson and Phillip Gross. They report shared voting and dispositive power over 436,736 Karyopharm common shares, reflecting their roles with affiliated Adage investment entities holding the securities.

How many Karyopharm Therapeutics (KPTI) shares does Adage report beneficially owning?

Adage and related reporting persons disclose beneficial ownership of 436,736 Karyopharm common shares. This total includes 15,414 shares issuable upon exercise of warrants held by an affiliated fund, and forms the basis for the reported 2.38% ownership of the outstanding common stock.

Does the Karyopharm (KPTI) Schedule 13G/A indicate an intent to influence control of the company?

The filing states the securities were acquired and are held in the ordinary course of business. It specifically certifies they were not acquired or held to change or influence control of Karyopharm, except for activities solely related to a nomination under the cited proxy rule.

What is the significance of the warrants mentioned in the Karyopharm (KPTI) filing?

The reported beneficial ownership includes 15,414 Karyopharm common shares issuable upon exercise of warrants. These warrant-linked shares are counted together with currently held common shares to reach the total of 436,736 shares and the 2.38% ownership percentage disclosed.

On what share count is Adage’s 2.38% Karyopharm (KPTI) ownership based?

The 2.38% figure is calculated using 18,310,283 Karyopharm common shares outstanding. This outstanding share number comes from Karyopharm’s Preliminary Proxy Statement on Schedule 14A, dated December 30, 2025, and assumes exercise of the warrants held by the Adage-affiliated fund.