0002047235 2026-09-30 2026-09-30 false 0002047235 8-K 2026-09-30 Winchester Bancorp, Inc. MD 001-42627 33-3361275 661 Main Street Winchester MA 01890 (781) 729-2130 false false false false Common Stock, par value $0.01 per share WSBK NASDAQ true false