X0306 4 2022-02-17 0 0001503802 Karyopharm Therapeutics Inc. KPTI 0001364719 Kauffman Michael C/O KARYOPHARM THERAPEUTICS INC. 85 WELLS AVENUE NEWTON MA 02459 1 0 0 0 Common Stock 2022-02-17 4 S 0 9079 12.1234 D 698983 D Common Stock 2022-02-17 4 S 0 9088 12.1234 D 904357 I By Spouse This transaction was a broker-assisted sale of shares to satisfy the payment of withholding tax liability incurred upon the vesting of restricted stock units and does not represent a discretionary trade by the reporting person. The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on February 17, 2022 on behalf of a group of employees of Karyopharm Therapeutics Inc. to satisfy the payment of withholding tax liability of such employees. This transaction was a broker-assisted sale of shares to satisfy the payment of withholding tax liability incurred upon the vesting of restricted stock units and does not represent a discretionary trade by the spouse of the reporting person. The sale price of the spouse of the reporting person's shares represents the weighted average price of all shares sold by a broker on February 17, 2022 on behalf of a group of employees of Karyopharm Therapeutics Inc. to satisfy the payment of withholding tax liability of such employees. /s/ Nancy Smith as Attorney-in-Fact for Michael Kauffman 2022-02-22