Karyopharm EVP reports PSU vesting; automated sale covers taxes

Rhea-AI Filing Summary

Stuart Poulton, EVP and Chief Development Officer of Karyopharm Therapeutics (KPTI), reported the vesting of 888 performance-based restricted stock units (PSUs) on 09/12/2025 after the company certified completion of enrollment in its Phase 3 SENTRY trial. Each PSU converts to one share, increasing his beneficial ownership to 28,111 shares. On 09/15/2025 he executed an automatic, broker-assisted sale of 401 shares at $6.43 to cover withholding taxes, leaving 27,710 shares beneficially owned. The PSUs were originally granted in February 2023 and vested upon certification by the Compensation Committee. The Form 4 was signed by an attorney-in-fact on 09/16/2025.

Positive

• Achievement of a Phase 3 clinical milestone (complete enrollment in the SENTRY trial) certified by the Compensation Committee, triggering PSU vesting
• Transparent disclosure of an automatic, broker-assisted sale to cover tax withholding rather than a discretionary insider trade

Negative

• None.

Insights

Financial Analyst

TL;DR: Vesting tied to a Phase 3 enrollment milestone signals clinical progress; transaction size is small relative to total float.

The reported vesting of 888 PSUs reflects achievement of a material clinical milestone for the SENTRY Phase 3 trial, which is directly relevant to Karyopharm's development program. While the dollar value realized by the reporting person is modest and the subsequent sale of 401 shares was an automated tax-withholding event, the certification by the Compensation Committee confirms a company-level operational achievement that could influence clinical timelines and investor sentiment. This disclosure is informational for modeling milestone-driven equity dilution and timing of potential future share releases tied to performance awards.

Corporate Governance Expert

TL;DR: Disclosure appears routine and compliant; the sale was non-discretionary under a pre-established plan.

The Form 4 documents standard insider reporting: earned PSUs certified by the Compensation Committee and an automatic broker-assisted sale to satisfy tax withholding. Filing by attorney-in-fact is properly indicated. There is no sign of discretionary trading or unusual timing; governance controls (compensation committee certification and durable sale instructions) are evident. The filing raises no immediate compliance concerns based on the information provided.

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

Poulton Stuart

(Last) (First) (Middle)

C/O KARYOPHARM THERAPEUTICS INC.

85 WELLS AVENUE

(Street)

NEWTON MA 02459

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Karyopharm Therapeutics Inc. [ KPTI ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, Chief Development Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/12/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/12/2025		A		888(1)	A	$0.0	28,111	D
Common Stock	09/15/2025		S(2)		401	D	$6.43	27,710	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents the number of shares of the issuer's common stock underlying performance-based restricted stock units ("PSUs") granted in February 2023 that have been earned based on the level of achievement of the clinical milestone for complete enrollment in the Company's Phase 3 SENTRY trial, as certified by the issuer's Compensation Committee on September 12, 2025. Each earned PSU represents the contingent right to receive one share of the issuer's common stock upon vesting. The earned PSUs vested on September 12, 2025.

2. This transaction was effected pursuant to a durable automatic sale instruction plan adopted by the reporting person on May 18, 2022, and represents a broker-assisted sale of shares to satisfy the payment of withholding tax liability incurred upon the vesting of PSUs. The sale does not represent a discretionary trade by the reporting person.

	/s/ Nancy Smith as Attorney-in-Fact for Stuart Poulton	09/16/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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FAQ

What triggered the 09/12/2025 vesting reported on the KPTI Form 4?

The vesting was triggered by achievement of the clinical milestone for complete enrollment in the Company's Phase 3 SENTRY trial, as certified by the Compensation Committee.

How many shares did Stuart Poulton receive upon vesting and how many did he own after the transactions?

888 PSUs vested, representing 888 shares; beneficial ownership increased to 28,111 shares and after a sale of 401 shares at $6.43 his beneficial ownership was 27,710 shares.

Why were 401 shares sold on 09/15/2025?

The 401-share sale was executed under a durable automatic sale instruction plan adopted on May 18, 2022, to satisfy withholding tax liability from the PSU vesting.

Were the transactions discretionary trades by the reporting person?

No. The sale was non-discretionary and broker-assisted under a pre-established automatic sale instruction plan; the vesting was the result of a certified milestone.

Who signed the Form 4 and when was it filed?

The form was signed by Nancy Smith as attorney-in-fact for Stuart Poulton on 09/16/2025.