Filed by M&T Bank Corporation

Pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12

of the Securities Exchange Act of 1934

Subject Company: Hudson City Bancorp, Inc.

(Commission File No. 0-26001)

The following document is filed herewith pursuant to Rule 425 under the Securities Act of 1933:

• Beginning on or about February 27, 2013, the following letter is first being mailed to M&T Bank Corporation shareholders of record as of February 20, 2013:

Cautionary Statements Regarding Forward-Looking Information

This filing contains forward looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 giving M&T Bank Corporation’s expectations or predictions of future financial or business performance or conditions. Forward-looking statements are typically identified by words such as “believe,” “expect,” “anticipate,” “intend,” “target,” “estimate,” “continue,” “positions,” “prospects” or “potential,” by future conditional verbs such as “will,” “would,” “should,” “could” or “may”, or by variations of such words or by similar expressions. These forward-looking statements are subject to numerous assumptions, risks and uncertainties which change over time. Forward-looking statements speak only as of the date they are made and we assume no duty to update forward-looking statements.

On August 27, 2012, M&T Bank Corporation, a New York corporation (“M&T”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Hudson City Bancorp, Inc., a Delaware corporation (“Hudson City”) and Wilmington Trust Corporation, a Delaware corporation and a wholly owned subsidiary of M&T (“WTC”). The Merger Agreement provides that, upon the terms and subject to the conditions set forth therein, Hudson City will merge with and into WTC, with WTC continuing as the surviving entity (the “Merger”). In addition to factors previously disclosed in M&T’s reports filed with the SEC and those identified elsewhere in this filing, the following factors among others, could cause actual results to differ materially from forward-looking statements or historical performance: ability to obtain regulatory approvals and meet other closing conditions to the Merger, including approval by M&T and Hudson City shareholders, on the expected terms and schedule; delay in closing the Merger; difficulties and delays in integrating the M&T and Hudson City businesses or fully realizing cost savings and other benefits; business disruption following the Merger; changes in asset quality and credit risk; the inability to sustain revenue and earnings growth; changes in interest rates and capital markets; inflation; customer acceptance of M&T products and services; customer borrowing, repayment, investment and deposit practices; customer disintermediation; the introduction, withdrawal, success and timing of business initiatives; competitive conditions; the inability to realize cost savings or revenues or to implement integration plans and other consequences associated with mergers, acquisitions and divestitures; economic conditions; and the impact, extent and timing of technological changes, capital management activities, and other actions of the Federal Reserve Board and legislative and regulatory actions and reforms.

Important Additional Information.

In connection with the Merger, M&T filed with the SEC on February 22, 2013 a Registration Statement on Form S-4 that includes a Joint Proxy Statement of M&T and Hudson City and a Prospectus of M&T (together with the Joint Proxy Statement, as amended, the “Joint Proxy Statement/Prospectus”), as well as other relevant documents concerning the proposed transaction. The S-4 has been declared effective and the Joint Proxy Statement/Prospectus is first being mailed to shareholders of M&T and Hudson City on or about February 27, 2013. SHAREHOLDERS OF M&T AND HUDSON CITY ARE URGED TO READ THE REGISTRATION STATEMENT AND THE JOINT PROXY STATEMENT/PROSPECTUS REGARDING THE MERGER AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THOSE DOCUMENTS, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION.

A free copy of the Joint Proxy Statement/Prospectus, as well as other filings containing information about M&T and Hudson City, may be obtained at the SEC’s Internet site (http://www.sec.gov). You are also able to obtain these documents, free of charge, from M&T at www.mtb.com under the tab “About Us” and then under the heading “Investor Relations” or from Hudson City by accessing Hudson City’s website at www.hcsbonline.com under the heading “Investor Relations.” Copies of the Joint Proxy Statement/Prospectus can also be obtained, free of charge, by directing a request to Investor Relations, One M&T Plaza, Buffalo, New York 14203, (716) 842-5445.

M&T and Hudson City and certain of their directors and executive officers may be deemed to be participants in the solicitation of proxies from the shareholders of M&T and Hudson City in connection with the Merger. Information about the directors and executive officers of M&T and their ownership of M&T common stock is set forth in the proxy statement for M&T’s 2012 annual meeting of shareholders, as filed with the SEC on Schedule 14A on March 7, 2012. Information about the directors and executive officers of Hudson City and their ownership of Hudson City common stock is set forth in the proxy statement for Hudson City’s 2012 annual meeting of shareholders, as filed with the SEC on a Schedule 14A on March 19, 2012. Additional information regarding the interests of those participants and other persons who may be deemed participants in the transaction may be obtained by reading the Joint Proxy Statement/Prospectus regarding the Merger. Free copies of this document may be obtained as described in the preceding paragraph.

One M&T Plaza

Buffalo, NY 14203

February 27, 2013

Dear M&T Bank Corporation Shareholder:

This year, M&T Bank Corporation will be holding both a Special Meeting of Shareholders and our customary Annual Meeting of Shareholders on Tuesday, April 16, 2013. Enclosed please find the Proxy Statement and voting materials to be used in connection with our Special Meeting of Shareholders to approve our acquisition of Hudson City Bancorp, Inc. that you are receiving as a shareholder of record on February 20, 2013.

If you are also a shareholder of record on February 28, 2013, you will receive a second package in the upcoming weeks that will contain our Annual Report, Proxy Statement and voting materials for our Annual Meeting of Shareholders.

Your vote with respect to both shareholder meetings is very important! Please follow the voting instructions contained in this package as well as the voting instructions that will be contained in the second package.

All inquiries with respect to the Special Meeting of Shareholders or the Annual Meeting of Shareholders should be made directly to M&T Bank Corporation at (716) 842-5138.

Thank you for your continued investment in M&T Bank Corporation.

Very truly yours,

Robert G. Wilmers

Chairman and Chief Executive Officer