X0508 4 2023-08-31 0001124105 CATALYST BIOSCIENCES, INC. CBIO 0001769866 Miller Seline E. C/O CATALYST BIOSCIENCES, INC. 611 GATEWAY BLVD., SUITE 120 SOUTH SAN FRANCISCO CA 94080 true SVP Finance; Interim CFO & PAO false Series Y Preferred Stock 2023-08-31 4 D 0 6.5 D 0 D On June 20, 2023, the Company's board of directors (the "Board") declared a dividend of one one-thousandth of a share of Series Y Preferred Stock, par value $0.001 per share (the "Preferred Stock"), for each outstanding share of common stock to common stockholders of record at 5:00 p.m. Eastern Time on June 30, 2023, in a transaction exempt from Section 16 under Rule 16a-9. The shares of Preferred Stock were distributed on June 30, 2023. As a result, the Reporting Person received the shares of Preferred Stock set forth above. The Preferred Stock was not convertible into, or exchangeable for, shares of any other class or series of stock or other securities of the Company On August 31, 2023, the Company filed, as approved by the Board, a certificate of elimination with the Secretary of State of the State of Delaware pursuant to which the outstanding shares of the Preferred Stock were eliminated. /s/ Seline Miller 2023-09-01