Karyopharm EVP sells 403 shares for tax withholding

Karyopharm Therapeutics EVP and Chief Development Officer Stuart Poulton reported a mix of equity award vesting and a related share sale.

Rhea-AI Filing Summary

Karyopharm Therapeutics EVP and Chief Development Officer Stuart Poulton reported a mix of equity award vesting and a related share sale. On May 13, 2026, he acquired 896 shares of common stock at $0.00 per share through earned performance-based restricted stock units tied to full enrollment of the Phase 3 XPORT-EC-042 trial. Those units vested the same day. On May 14, 2026, 403 shares were sold at $9.50 per share under a durable automatic sale instruction plan to cover withholding tax liabilities from the vesting, and the sale was not a discretionary trade. After these transactions, he directly owned 94,821 shares of common stock.

Insider Trade Summary

Net Seller: 403 shares

Net Sell 2 txns

Insider Poulton Stuart

Role EVP, Chief Development Officer

Sold 403 shs ($4K)

Type	Security	Shares	Price	Value
Sale	Common Stock	403	$9.50	$4K
Grant/Award	Common Stock	896	$0.00	$0.00

Holdings After Transaction: Common Stock — 94,821 shares (Direct)

Footnotes (2)

1. F1. Represents the number of shares of the issuer's common stock underlying performance-based restricted stock units ("PSUs") granted in February 2024 that have been earned based on the level of achievement of the clinical milestone for complete enrollment in the Company's Phase 3 XPORT-EC-042 trial, as certified by the issuer's Compensation Committee on May 13, 2026. Each earned PSU represents the contingent right to receive one share of the issuer's common stock upon vesting. The earned PSUs vested on May 13, 2026.
2. F2. 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.

Key Figures

Shares acquired via PSUs: 896 shares Shares sold for taxes: 403 shares Sale price per share: $9.50 per share +2 more

5 metrics

Shares acquired via PSUs 896 shares Earned and vested on May 13, 2026 from performance-based RSUs

Shares sold for taxes 403 shares Open-market sale on May 14, 2026 to cover withholding tax

Sale price per share $9.50 per share Price for 403-share tax-related sale on May 14, 2026

Shares held after transactions 94,821 shares Direct ownership of common stock following PSU vesting and sale

PSU grant date February 2024 Grant date of performance-based RSUs that later vested

Key Terms

performance-based restricted stock units ("PSUs"), durable automatic sale instruction plan, withholding tax liability, Phase 3 XPORT-EC-042 trial, +1 more

5 terms

performance-based restricted stock units ("PSUs") financial

"Represents the number of shares of the issuer's common stock underlying performance-based restricted stock units ("PSUs") granted in February 2024..."

durable automatic sale instruction plan financial

"This transaction was effected pursuant to a durable automatic sale instruction plan adopted by the reporting person on May 18, 2022..."

withholding tax liability financial

"...represents a broker-assisted sale of shares to satisfy the payment of withholding tax liability incurred upon the vesting of PSUs."

Phase 3 XPORT-EC-042 trial technical

"...achievement of the clinical milestone for complete enrollment in the Company's Phase 3 XPORT-EC-042 trial..."

Compensation Committee financial

"...as certified by the issuer's Compensation Committee on May 13, 2026."

A compensation committee is a group within a company's leadership responsible for setting and reviewing how much top executives and employees are paid, including salaries, bonuses, and benefits. It matters to investors because fair and effective pay decisions can influence a company's performance, leadership motivation, and overall governance, helping ensure that the company’s management is aligned with shareholders’ interests.

FAQ

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

What insider transactions did Karyopharm (KPTI) EVP Stuart Poulton report?

Stuart Poulton reported earning 896 shares of Karyopharm common stock from performance-based RSUs, then selling 403 shares at $9.50. The sale occurred the next day and was tied to tax withholding obligations from the vesting event.

Why did Karyopharm (KPTI) EVP Stuart Poulton sell 403 shares?

The 403-share sale at $9.50 was executed to satisfy withholding tax liabilities from vesting PSUs. It occurred under a durable automatic sale instruction plan adopted in May 2022, and was not a discretionary trade by the executive.

What performance milestone triggered Stuart Poulton’s PSUs at Karyopharm (KPTI)?

The PSUs were earned when Karyopharm completed enrollment in its Phase 3 XPORT-EC-042 trial. The Compensation Committee certified achievement of this clinical milestone on May 13, 2026, causing the performance-based restricted stock units to vest and convert into common shares.

How many Karyopharm (KPTI) shares does Stuart Poulton hold after these transactions?

Following the PSU vesting and related tax sale, Stuart Poulton directly holds 94,821 shares of Karyopharm common stock. This figure reflects his updated ownership after acquiring 896 shares from PSUs and selling 403 shares to cover associated withholding taxes.

What are performance-based restricted stock units (PSUs) in the Karyopharm (KPTI) filing?

In this context, PSUs are equity awards that convert into common shares only if specific performance goals are met. Poulton’s PSUs were granted in February 2024 and were earned when a Phase 3 trial enrollment milestone was achieved and certified by the Compensation Committee.

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

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Accepted by SEC EDGAR 05/15/2026 - 04:08 PM EDT Learn about SEC filing dates

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
Estimated average burden
hours per response:			0.5

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Poulton Stuart

(Last) (First) (Middle)

C/O KARYOPHARM THERAPEUTICS INC.

85 WELLS AVENUE

(Street)

NEWTON MASSACHUSETTS 02459

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/13/2026

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

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

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

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	05/13/2026		A		896(1)	A	$0.0	95,224	D
Common Stock	05/14/2026		S(2)		403	D	$9.5	94,821	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 2024 that have been earned based on the level of achievement of the clinical milestone for complete enrollment in the Company's Phase 3 XPORT-EC-042 trial, as certified by the issuer's Compensation Committee on May 13, 2026. Each earned PSU represents the contingent right to receive one share of the issuer's common stock upon vesting. The earned PSUs vested on May 13, 2026.

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	05/15/2026
	** 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).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)