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                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                     --------------------------------------



                                    FORM 8-K

                                 CURRENT REPORT
                    PURSUANT TO SECTION 13 OR 15 (D) OF THE
                        SECURITIES EXCHANGE ACT OF 1934


                        DATE OF REPORT: AUGUST 13, 1998


                                   UST CORP.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)



                                                                               
             MASSACHUSETTS                             0-9623                         04-2436093
    (STATE OR OTHER JURISDICTION OF            (COMMISSION FILE NO.)         (IRS EMPLOYER IDENTIFICATION
             INCORPORATION)                                                              NO.)




                                                                                 
            40 COURT STREET                        (617) 726-7000                        02108
         BOSTON, MASSACHUSETTS            (REGISTRANT'S TELEPHONE NUMBER,             (ZIP CODE)
(ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)        INCLUDING AREA CODE)

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ITEM 2. ACQUISITION OF ASSETS.

Acquisition of Affiliated Community Bancorp., Inc.

         On December 15, 1997, UST Corp., (the "Company") executed an agreement
with Affiliated Community Bancorp, Inc. ("Affiliated") of Waltham,
Massachusetts, pursuant to which the Company agreed to acquire Affiliated (the
"Affiliated Acquisition"). On August 7, 1998, the Company consummated the
Affiliated Acquisition. Affiliated is a bank holding company for three community
banks, Lexington Savings Bank, The Federal Savings Bank, and Middlesex Bank &
Trust Company, which operate an aggregate of thirteen branch offices located in
Eastern Middlesex county. The transaction was structured as a tax-free exchange
of 1.41 shares of the Company's common stock for each share of Affiliated common
stock and accounted for as a pooling of interests. As of the closing date, the
transaction was valued at approximately $225 million. A total of 9.4 million
shares of the Company's common stock were issued in exchange for the 6.7 million
Affiliated shares outstanding at the closing date.

         As contemplated by the agreement pursuant to the terms of which the
Acquisition was consummated (the "Affiliation Agreement") Middlesex Bank & Trust
Company, a $28 million bank was sold for $8.24 million to a private investor,
unaffiliated with the Company, following the consummation of the Affiliated
Acquisition.

         The Company hereby files its Unaudited Pro Forma Combined Financial
Statements and Notes thereto as of March 31, 1998, in connection with the
Affiliated Acquisition:

ITEM 5.  OTHER EVENTS.

         In connection with the acquisition of Affiliated, Timothy J. Hansberry,
formerly President and Chief Executive Officer of Affiliated became, as of
August 7, 1998, Vice Chairman and Chief Operating Officer of the Company and
President and Chief Operating Officer of the Company's principal banking
subsidiary, USTrust. John G. Fallon, formerly Executive Vice President,
Treasurer and Chief Financial Officer of Affiliated became an Executive Vice
President of the Company and USTrust.

         Furthermore, as contemplated by the Affiliation Agreement, on September
15, 1998 (the date of the first Board Meeting of the Company subsequent to the
consummation of the Acquisition) five former Directors of Affiliated (including
Mr. Hansberry) will become Directors of the Company. The five individuals to be
elected a Director of the Company on September 15, 1998 are:

        NEW DIRECTOR                             PRINCIPAL OCCUPATION(S)
        ------------                             -----------------------

  Timothy J. Hansberry             Vice Chairman and Chief Operating Officer
                                   of the Company and former President and
                                   Chief Executive Officer of Affiliated

  Kendrick G. Bushnell             Retired business executive and independent
                                   management consultant

  Jack E. Chappell                 Retired business executive and former
                                   Chairman of the Board of Affiliated

  Edward S. Heald                  Corporate Vice President and Branch Manager,
                                   A. G. Edwards & Sons, Inc. (a financial
                                   services firm), Newton, Massachusetts

  James E. McCobb, Jr.             Former President and Chief Executive Officer
                                   The Federal Savings Bank, a banking
                                   subsidiary of Affiliated
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ITEM 7.  FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

   (a)   Historical financial statements of Affiliated for the year ended
         December 31, 1997 (Incorporated by reference to UST Corp. and 
         Affiliated's Registration Statement on Form S-4 (Registration 
         No. 333-52115) filed with the Securities and Exchange Commission on 
         May 11, 1998.)

    (b)  Unaudited Pro Forma Condensed Combined Statements of Income for the
         years ended December 31, 1997, 1996 and 1995 (Incorporated by reference
         to UST Corp. and Affiliated's Registration Statement on Form S-4
         (Registration No. 333-52115) filed with the Securities and Exchange
         Commission on May 11, 1998.)

    (c)  Unaudited financial statements of Affiliated for the three months ended
         March 31, 1998 (Incorporated by reference to Affiliated's Form 10-Q
         (Commission File No. 0-27014) for the quarter ended March 31, 1998.

    (d)  Unaudited Pro Forma Combined Financial Statements and Notes thereto
         (Exhibit 99.1)

    (e)  Exhibits

          99.1    Unaudited Pro Forma Combined Financial Statements and Notes
                  thereto

          99.2    Consent of Arthur Andersen LLP, Independent Public Accountants
                  of Affiliated Community Bancorp, Inc.

          99.3    Consent of KPMG Peat Marwick LLP, Independent Public
                  Accountants of The Federal Savings Bank
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                                   SIGNATURES


         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Company has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                  UST Corp.



                                  /s/  James K. Hunt
                                  ----------------------------------------
                                  James K. Hunt
                                  Executive Vice President, Treasurer and
                                  Chief Financial Officer

Dated:  August 13, 1998