X0508 4 2025-10-28 0001849867 Catalyst Bancorp, Inc. CLST 0001885818 Kleiser Kirk E. C/O CATALYST BANCORP INC 235 N COURT ST OPELOUSAS LA 70570 true false false false 0 Common Stock 2025-10-28 4 S 0 1500 13.43 D 3250 I By Kleiser Enterprises Corporation Common Stock 2025-10-28 4 S 0 2500 13.39 D 750 I By Kleiser Enterprises Corporation Common Stock 2025-10-28 4 S 0 750 13.3974 D 0 I By Kleiser Enterprises Corporation Common Stock 2025-10-28 4 P 0 100 13.40 A 13099 I By IRA Common Stock 2025-10-28 4 P 0 4650 13.4099 A 17749 I By IRA Common Stock 24522 D Common Stock 1000 I By K & G On the Geaux LLC Common Stock 5000 I By K Kleiser LLC Common Stock 3100 I By Spouse in IRA Common Stock 900 I By Spouse Stock Option (Right to Buy) 13.30 2032-09-01 Common Stock 21160 21160 D Stock Option (Right to Buy) 12.08 2035-06-10 Common Stock 2645 2645 D Includes 3,384 shares granted pursuant to the Issuer's 2022 Recognition and Retention Plan and Trust Agreement that reflect the unvested portion of a grant amount originally covering 8,464 shares that commenced vesting 20% per year on September 1, 2023. The 1,000 shares are held by the K&G On the GEAUX LLC of which the reporting person is a senior managing member and 60% owner. The 5,000 shares are held by the K Kleiser LLC of which the reporting person is the sole member. The options are vesting at a rate of 20% per year commenced on September 1, 2023. The options vest at a rate of 20% per year commencing on June 10, 2026. /s/ Jutta Codori by P.O.A. for Kirk E. Kleiser 2025-10-30