As filed with the Securities and Exchange Commission on November 4, 2026

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

WINCHESTER BANCORP, INC.

(Exact name of registrant as specified in its charter)

661 Main Street

Winchester, Massachusetts 01890

(781) 729-2130

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

WINCHESTER BANCORP, INC.
2026 EQUITY INCENTIVE PLAN
(Full title of the plan)

John A. Carroll

President and Chief Executive Officer

Winchester Bancorp, Inc.

661 Main Street

Winchester, Massachusetts 01890

(781) 729-2130

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Samantha M. Kirby, Esq.

Covington & Burling LLP

One International Place, Suite 1020

Boston, Massachusetts 02110

(617) 603-8800

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided to Section 7(a)(2)(B) of the Securities Act. ¨

PART I

INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS

Items 1 and 2.

The information required by Item 1 and Item 2 of Part I of Form S-8 to be contained in the Section 10(a) prospectus

is omitted from this Registration Statement in accordance with Rule 428 under the Securities Act of 1933, as

amended (the “Securities Act”), and the introductory note to the instructions to Part I of Form S-8. In accordance

with the rules and regulations of the Securities and Exchange Commission (the “Commission”) and the instructions

to Form S-8, such documents are not being filed with the Commission either as part of this Registration Statement or

as prospectuses or prospectus supplements pursuant to Rule 424 under the Securities Act. Winchester Bancorp, Inc. (the “Corporation”) will deliver the documents containing the information specified in Part I to participants as required by Rule 428(b)(1) under the Securities Act.

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

The following documents, filed with the Commission pursuant to the Securities Exchange Act of 1934, as amended

(the “Exchange Act”), are hereby incorporated by reference in this Registration Statement:

All documents subsequently filed by the Corporation pursuant to Sections 13(a), 13(c), 14, and 15(d) of the Securities Exchange Act of 1934 (the “Exchange Act”), prior to the filing of a post-effective amendment to this Registration Statement which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents.

Any statement contained in a document incorporated or deemed to be incorporated by reference in this Registration Statement shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained in this Registration Statement or in any other subsequently filed document that also is incorporated or is deemed to be incorporated by reference in this Registration Statement modifies or supersedes such prior statement. Any statement contained in this Registration Statement shall be deemed to be modified or superseded to the extent that a statement contained in a subsequently filed document that is or is deemed to be incorporated by reference in this Registration Statement modifies or supersedes such prior statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

Item 4. Description of Securities.

Not applicable.

Item 5. Interests of Named Experts and Counsel.

Not applicable.

Item 6. Indemnification of Directors and Officers.

Article 10 of the Articles of Incorporation of Winchester Bancorp, Inc. (the “Corporation”) sets forth the circumstances under which directors, officers, employees and agents of the Corporation may be insured or indemnified against liability which they may incur in their capacities as such:

ARTICLE 10. Indemnification, etc. of Directors and Officers.

A. Indemnification. The Corporation shall indemnify (1) its current and former directors and officers, whether serving the Corporation or at its request any other entity, to the fullest extent required or permitted by the Maryland General Corporation Law (the “MGCL”) now or hereafter in force, including the advancement of expenses under the procedures and to the fullest extent permitted by law, and (2) other employees and agents to such extent as shall be authorized by the Board of Directors and permitted by law; provided, however, that, except as provided in Section B of this Article 10 with respect to proceedings to enforce rights to indemnification, the Corporation shall indemnify any such indemnitee in connection with a proceeding (or part thereof) initiated by such indemnitee only if such proceeding (or part thereof) was authorized by the Board of Directors of the Corporation.

B. Procedure. If a claim under Section A of this Article 10 is not paid in full by the Corporation within sixty (60) days after a written claim has been received by the Corporation, except in the case of a claim for an advancement of expenses, in which case the applicable period shall be twenty (20) days, the indemnitee may at any time thereafter bring suit against the Corporation to recover the unpaid amount of the claim. If successful in whole or in part in any such suit, or in a suit brought by the Corporation to recover an advancement of expenses pursuant to the terms of an undertaking, the indemnitee shall also be entitled to be reimbursed the expense of prosecuting or defending such suit. It shall be a defense to any action for advancement of expenses that the Corporation has not received both (i) an undertaking as required by law to repay such advances if it shall ultimately be determined that the standard of conduct has not been met and (ii) a written affirmation by the indemnitee of his or her good faith belief that the standard of conduct necessary for indemnification by the Corporation has been met. In (i) any suit brought by the indemnitee to enforce a right to indemnification hereunder (but not in a suit brought by the indemnitee to enforce a right to an advancement of expenses) it shall be a defense that, and (ii) any suit by the Corporation to recover an advancement of expenses pursuant to the terms of an undertaking the Corporation shall be entitled to recover such expenses upon a final adjudication that, the indemnitee has not met the applicable standard for indemnification set forth in the MGCL. Neither the failure of the Corporation (including its Board of Directors, independent legal counsel, or its stockholders) to have made a determination before the commencement of such suit that indemnification of the indemnitee is proper in the circumstances because the indemnitee has met the applicable standard of conduct set forth in the MGCL, nor an actual determination by the Corporation (including its Board of Directors, independent legal counsel, or its stockholders) that the indemnitee has not met such applicable standard of conduct, shall create a presumption that the indemnitee has not met the applicable standard of conduct, or, in the case of such a suit brought by the indemnitee, be a defense to such suit. In any suit brought by the indemnitee to enforce a right to indemnification or to an advancement of expenses hereunder, or by the Corporation to recover an advancement of expenses pursuant to the terms of an undertaking, the burden of proving that the indemnitee is not entitled to be indemnified, or to such advancement of expenses, under this Article 10 or otherwise, shall be on the Corporation.

C. Non-Exclusivity. The rights to indemnification and to the advancement of expenses conferred in this Article 10 shall not be exclusive of any other right that any Person may have or hereafter acquire under any statute, these Articles, the Corporation’s Bylaws, any agreement, any vote of stockholders or the Board of Directors, or otherwise.

D. Insurance. The Corporation may maintain insurance, at its expense, to insure itself and any director, officer, employee or agent of the Corporation or another corporation, partnership, joint venture, trust or other enterprise against any expense, liability or loss, whether or not the Corporation would have the power to indemnify such Person against such expense, liability or loss under the MGCL.

E. Miscellaneous. The Corporation shall not be liable for any payment under this Article 10 in connection with a claim made by any indemnitee to the extent such indemnitee has otherwise actually received payment under any insurance policy, agreement, or otherwise, of the amounts otherwise indemnifiable hereunder. The rights to indemnification and to the advancement of expenses conferred in Sections A and B of this Article 10 shall be contract rights and such rights shall continue as to an indemnitee who has ceased to be a director or officer and shall inure to the benefit of the indemnitee’s heirs, executors and administrators.

F. Limitations Imposed by Federal Law. Notwithstanding any other provision set forth in Article 10, in no event shall any payments made by the Corporation pursuant to this Article 10 exceed the amount permissible under applicable federal law, including, without limitation, Section 18(k) of the Federal Deposit Insurance Act and the regulations promulgated thereunder.

Any repeal or modification of this Article 10 by the stockholders of the Corporation or the Board of Directors shall not in any way diminish any rights to indemnification or advancement of expenses of such director or officer or the obligations of the Corporation arising hereunder with respect to events occurring, or claims made, while this Article 10 is in force.

Item 7. Exemption from Registration Claimed.

None.

Item 8. Exhibits.

The exhibits to this Registration Statement are listed in the Exhibit Index attached hereto and incorporated by reference herein.

* Filed herewith

(1) Incorporated herein by reference to the Registrant’s Form S-1 Registration Statement initially filed with the SEC on December 12, 2024 (File No. 333-283752)

Item 9. Undertakings.

1.             The undersigned Corporation hereby undertakes:

(a) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement:

(i) To include any prospectus required by section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Securities and Exchange Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20 percent change in the maximum aggregate offering price set forth in the “Calculation of Filing Fee Tables” table in the effective Registration Statement.

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the Registration Statement;

Provided, however, that paragraphs (a)(i) and (a)(ii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Securities and Exchange Commission by the Corporation pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference herein.

(b) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered herein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

2.             The undersigned Corporation hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the Corporation’s annual report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

3.             Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Corporation pursuant to the foregoing provisions, or otherwise, the Corporation has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Corporation of expenses incurred or paid by a director, officer or controlling person of the Corporation in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Corporation will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and that it has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Westerly, Rhode Island, on the 4th day of November, 2026.

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that we, the undersigned officers and directors of Winchester Bancorp, Inc., hereby severally constitute John A. Carroll and Elda Heller, and each of them singly, our true and lawful attorneys with full power to them, and each of them singly, to sign for us and in our names in the capacities indicated below and in such other capacities as the undersigned may from time to time serve in the future, the registration statement filed herewith and any and all amendments (including post-effective amendments) to said registration statement (or any registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended), and generally to do all such things in our names and in our capacities as officers and directors to enable Winchester Bancorp, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission, hereby ratifying and confirming our signatures as they may be signed by our said attorneys, or any of them, to said registration statement and any and all amendments thereto.

Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed by the following persons in the capacities and on the dates indicated.