WASHINGTON TRUST BANCORP INC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 10-K

(Mark One)

Commission file number:001-32991

WASHINGTON TRUST BANCORP, INC.

(Exact name of registrant as specified in its charter)

(401)348-1200

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(g) of the Act: NONE

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.☐Yes☒No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.☐Yes☒No

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.☒Yes ☐No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).☒Yes ☐No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definitions of “large accelerated filer,” “accelerated filer,” and “smaller reporting 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 accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to Section 240.10D-1(b).☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).☐Yes☒No

The aggregate market value of voting stock held by non-affiliates of the registrant at June 30, 2025 was $539,528,713 based on a closing sales price of $28.28 per share as reported on the Nasdaq Global Select Market, which includes $19,517,131 held by The Washington Trust Company, of Westerly under trust agreements and other instruments.

The number of shares of the registrant’s common stock, $.0625 par value per share, outstanding as of January 31, 2026 was 19,039,948.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Registrant’s Proxy Statement dated March 17, 2026 for the Annual Meeting of Shareholders to be held on April 28, 2026 are incorporated by reference into Part III of this Form 10-K.

FORM 10-K

WASHINGTON TRUST BANCORP, INC.

For the Year Ended December 31, 2025

TABLE OF CONTENTS

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