NasdaqFinancialsSavings Institutions, Not Federally CharteredWINCHESTER, MA

Winchester Bancorp, Inc. WSBK

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Estimated market cap $129.11M9.30M shares, shares as of Sep 10, 2026CIK 2047235

Insider trades, 12 mo

6 buys · 0 sells

$145.3K bought, open market

Congress trades, 24 mo

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No disclosed trades

13F holders, Q3 2026

4.9% of shares · 2 added

13F holders

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Lobbying, 12 mo

—

No lobbying filings

Federal contracts, 12 mo

—

None matched

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IPO prospectus

Updated

Winchester Bancorp, Inc.’s initial public offering: where it stands and what the registration statement says.

Updated · Proposed ticker WSBK, Nasdaq Capital Market · First filed Dec 12, 2024

Read from the S-1/A filed Feb 6, 2025 · Read it on sec.gov ↗

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AI summary of the prospectus. Written by AI from the parts of the prospectus listed in the filing, and checked against its text. This is information, not investment advice.

All filings of this IPO Read the S-1/A on sec.gov ↗

IPO prospectus

Winchester Bancorp, Inc.’s initial public offering: where it stands and what the registration statement says.

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Latest 10-Q

Q3 2026

What changed in Winchester Bancorp, Inc.'s latest quarterly report, compared with the one before.

Filed Nov 4, 2026 · Quarter ended Sep 30, 2026

Compared with the 10-K for the period ended Jun 30, 2026. Sections compared: management's discussion, risk factors, legal proceedings and controls and procedures.

Read the 10-Q on sec.gov ↗Filing index ↗

Latest 10-Q

What changed in Winchester Bancorp, Inc.'s latest quarterly report, compared with the one before.

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Insider trades

6 in 12 mo

Open-market trades from Form 4. 10b5-1 marks a plan set in advance.

No open-market insider trades reported since May 26, 2026. Insiders have two business days to file.

Recent insider trades

Edward J. Merritt Director	May 26 Form 4 ↗	Buy	+$11.7K 915 sh @ $12.76	+8.5%
John A. Carroll President & CEO, Director	May 21 Form 4 ↗	Buy	+$638 50 sh @ $12.75	+7.3%
John Ingalls Snow III Director	May 7 Form 4 ↗	Buy	+$2,554 200 sh @ $12.77	+5.9%
John Ingalls Snow III Director	May 7 Form 4 ↗	Buy	+$19.5K 1,525 sh @ $12.79	+5.9%
John Ingalls Snow III Director	May 5 Form 4 ↗	Buy	+$78.6K 6,110 sh @ $12.87	+5.1%

All WSBK insider trades →Planned sales (Form 144): see notices

Insider trades

Open-market trades from Form 4. 10b5-1 marks a plan set in advance.

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13F holders

451,392 shares

14 funds report WSBK. Values checked against market prices.

Funds own 8.4% of shares (Q2 2026)

21 funds hold the stock.

Q3 2026: 4.9% · 5,560 of ~8,900 funds reported so far

Q2 20256.7%
Q3 20257.6%
Q4 20258.3%
Q1 20268.1%
Q2 20268.4%
Q3 2026 (so far)4.9%

Q3 2026. 2 new, 2 added to, 2 trimmed, 9 exited since Q2 2026.

Top 13F holders
#
1	Vanguard Capital Management LLC 13F ↗	178,941	$2.3M	unchanged
2	Northstar Financial Companies, Inc. 13F ↗	70,000	$903.7K	unchanged
3	Oppenheimer & Close, LLC 13F ↗	50,000	$645.5K	unchanged
4	Renaissance Technologies LLC 13F ↗	34,400	$444.1K	+9.6%
5	Geode Capital Management, LLC 13F ↗	28,199	$364.3K	-2.9%
6	Vanguard Fiduciary Trust Co 13F ↗	22,708	$293.2K	unchanged
7	Steward Partners Investment Advisory, LLC 13F ↗	19,127	$246.9K	unchanged
8	EagleClaw Capital Managment, LLC 13F ↗	16,000	$206.6K	unchanged
9	LPL Financial LLC 13F ↗	15,500	$200.1K	unchanged
10	BlackRock, Inc. 13F ↗	13,598	$175.6K	-4.3%

Download CSV Every fund that holds WSBK, not only these ten. A download holds at most 10,000 rows; narrow the filters to get a smaller slice.

13F holders

Funds that report this stock, checked against market prices.

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Trades by members of Congress

Disclosed in dollar ranges, up to 45 days after the trade.

No recent congressional trades for this company.

Trades by members of Congress

Disclosed in dollar ranges, up to 45 days after the trade.

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Lobbying

What Winchester Bancorp, Inc. and its lobbying firms report each quarter.

No recent lobbying filings for this company.

Lobbying

What Winchester Bancorp, Inc. and its lobbying firms report each quarter.

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Institutional ownership over time

How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.

Funds holding the stock

Shares they report

Funds holding the stock by quarter

Q2 2025	18	—	620,236	$5.6M
Q3 2025	22	+4	708,264	$6.8M
Q4 2025	21	-1	771,277	$8.1M
Q1 2026	19	-2	750,531	$9.5M
Q2 2026	21	+2	784,121	$10.3M
Q3 2026	14	-7	451,392	$5.8M

Each point is a quarter-end, from Q2 2025 to Q3 2026. A fund's 13F lists its long positions in US-listed securities as of the last day of the quarter and arrives up to 45 days later, so each point shows holdings at quarter-end, not on the day they were reported.

Common shares only; options and bonds are left out. When a fund amends a report, the amended version is the one counted.

The history follows the company's current CUSIP number (97269D103). If the company's shares were ever re-issued under a different CUSIP, the quarters before the change are not part of this series, so the first point (Q2 2025) can be later than the stock's first appearance in 13F reports.

Share counts are adjusted for stock splits; none took place between these quarters. Values are in dollars as reported at the time and are not adjusted.

A quarter appears once our daily update has built its summary. If a summary cannot be built, older reports are kept and the chart shows the quarters it has until the next update repairs it.

Institutional ownership over time

How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.

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More filings and data

Each opens the table.

Ownership stakesNone in 12 mo 8-K events3 in 90 days PatentsNone on record Short interestFINRA · updated Oct 15 Planned insider salesNone in 12 mo Executive payNone on record Wikipedia attentionNone on record SEC enforcementNone on record IPO history1 registration Ownership stakes…8-K events…Patents…Short interest…Planned insider sales…Executive pay…Wikipedia attention…SEC enforcement…

About the company

The basics from the company’s SEC registration.

Legal name: Winchester Bancorp, Inc./MD/
Address: 661 MAIN STREET, WINCHESTER, MA 01890
Phone: (781) 729-2130
Fiscal year ends: Dec 31
Filer category: emerging growth company
Incorporated in: MD
Listed as: WSBK (Nasdaq)
SEC filings: All filings on SEC EDGAR ↗

About the company

The basics from the company’s SEC registration.

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$13.89+$0.07 (+0.50%) Nov 13 close

1M3M1Y

Oct 13, 2026Low $12.91 · High $13.89Nov 13, 2026

Aug 13, 2026Low $12.70 · High $13.89Nov 13, 2026

Nov 13, 2025Low $9.56 · High $13.89Nov 13, 2026

Congress purchase Congress sale Insider sale over $1M

Adjusted for stock splits; not for dividends. Where prices come from.

Live chart

Intraday and historical prices from TradingView. Quotes may be delayed.

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Information, not investment advice. Company matching is automatic; check the source before relying on one row.