Winchester Bancorp, Inc. Common Stock (WSBK) Institutional Ownership

Based on Q1 2026 13F filings, institutional ownership of Winchester Bancorp, Inc. Common Stock stands at 8.0%, held across 19 reporting institutions.

MANGROVE PARTNERS is the largest reported institutional holder of WSBK, with approximately 186,201 shares worth $0.00B as of Q1 2026.

Yes — 2 widely-followed marquee investors appear among the top 25 institutional holders of WSBK, including RENAISSANCE TECHNOLOGIES LLC, MILLENNIUM MANAGEMENT LLC.

Our composite Smart Money Score for WSBK is 55 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.

2 institutions opened new positions in WSBK during Q1 2026, while 5 fully exited. 13 added to existing positions and 3 trimmed.

WSBK institutional ownership rose by 1.63 percentage points quarter-over-quarter, with a net change of -3 holders.

The top 10 institutions account for 91.1% of all reported 13F value in WSBK, and the top 25 account for 100.0%.

All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.