SECURITIES AND EXCHANGE COMMISSION

                    Washington, D.C.  20059



                          SCHEDULE 13G


           Under the Securities Exchange Act of 1934

                       (Amendment No. 2)





NAME OF ISSUER:    Ambac, Inc.


TITLE OF CLASS OF SECURITIES:          Common Stock




CUSIP NUMBER:      023139-108





Check the following box if a fee is being paid with this 
statement: [    ]






<PAGE>


CUSIP NO.  023139-108



(1)   Names of Reporting Persons       MELLON BANK CORPORATION
      SS or IRS Identification Nos.         IRS No. 25-1233834
      of Above Persons


(2)   Check the Appropriate Box        (a)
      if a Member of a Group
      (See Instructions)               (b)


(3)   SEC Use Only


(4)   Citizenship or Place                        United States
      of Organization


Number of Shares   (5)  Sole Voting      491,000
Beneficially            Power
Owned by Each      
Reporting Person
With               (6)  Shared Voting      1,000
                        Power
                   
                   (7)  Sole
                        Dispositive      684,000
                        Power
                                                          
                   (8)  Shared
                        Dispositive      355,000
                        Power


(9)   Aggregate Amount Beneficially
      Owned by Each Reporting Person   1,039,000


(10)  Check if the Aggregate Amount
      in Row (9) Excludes Certain
      Shares (See Instructions)


(11)  Percent of Class Represented     2.94
      by Amount in Row (9)


(12)  Type of Reporting Person         HC
      (See Instructions)






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               SECURITIES AND EXCHANGE COMMISSION
                    Washington, D.C.  20549

                          SCHEDULE 13G
        (Under the Securities and Exchange Act of 1934)

Item 1(a)         Name of Issuer:

                  Ambac, Inc.

Item 1(b)    Address of Issuer's Principal Executive Offices:

                  1 State Street Plaza
                  New York, NY  10004

Item 2 (a)   Name of Person Filing:

                  Mellon Bank Corporation and Subsidiaries 
                  (including but not limited to the 
                  Subsidiaries of The Boston Company, Inc.) as 
                  listed on Exhibit I

Item 2(b)    Address of Principal Business Office, or if None, 
             Residence:

                  Mellon Bank Corporation
                  One Mellon Bank Center
                  Pittsburgh, Pennsylvania  15258

Item 2(c)    Citizenship:

                  United States

Item 2(d)    Title of Class of Securities:

                  Common Stock

Item 2(e)    CUSIP Number:

                  023139-108

Item 3       If this statement is filed pursuant to Rules 
             13d-1(b), or 13d-2(b), check whether the person 
             filing is a:

             (a)  [ ]   Broker or Dealer registered under 
                        Section 15 of the Act.
             (b)  [ ]   Bank as defined in Section 3(a)(6) of 
                        the Act.








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<PAGE>


SCHEDULE 13G  (Continued)


             (c)  [ ]   Insurance Company as defined in Section 
                        3(a)(19) of the Act.
             (d)  [ ]   Investment Company registered under 
                        Section 8 of the Investment Company Act.
             (e)  [ ]   Investment Advisor registered under 
                        Section 203 of the Investment Advisers 
                        Act of 1940.
             (f)  [ ]   Employee Benefit Plan, Pension Fund 
                        which is subject to the provisions of 
                        the Employee Retirement Income Security 
                        Act of 1974 or Endowment Fund; see 
                        Section 240.13d-1(b)(1)(ii)(F).
             (g)  [x]   Parent Holding Company, in accordance 
                        with Section 240.13-d(1)(b)(ii)(G).  
                        (Note:  See Item 7)
             (h)  [ ]   Group, in accordance with Section 
                        240.13d(1)(b)(ii)(H).

Item 4  Ownership:

        (a)  Amount beneficially owned:           1,039,000*
             * See Exhibit II (C)

        (b)  Percent of class:                    2.94

        (c)  Number of shares as to
             which person has:

          (i)     Sole power to vote or
                  to direct the vote:               491,000

         (ii)     Shared power to vote
                  or to direct the vote:              1,000

         (iii)    Sole power to dispose
                  or to direct the
                  disposition of shares:            684,000

         (iv)     Shared power to dispose
                  or to direct the
                  disposition of shares:            355,000

Item 5  Ownership of Five Percent or Less of a Class:

             This statement is being filed to report the fact 
             that as of the date hereof the reporting person 
             has ceased to be the beneficial owner of more than 
             five percent of the class of securities.







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SCHEDULE 13G  (Continued)


Item 6  Ownership of More than Five Percent on Behalf of 
        Another Person:

             N/A

Item 7  Identification and Classification of the Subsidiary 
        Which Acquired the Security Being Reported by the 
        Parent Holding Company:

             This Schedule is filed on behalf of Mellon Bank 
             Corporation and Subsidiaries (including but not 
             limited to the Subsidiaries of The Boston Company, 
             Inc.) as noted on Exhibit I.

Item 8  Identification and Classification of Members of the 
        Group:

             N/A

Item 9  Notice of Dissolution of Group:

             N/A

Item 10 Certification:

             By signing below I certify that, to the best of my 
             knowledge and belief, the securities referred to 
             above were acquired in the ordinary course of 
             business and were not acquired for the purpose of 
             and do not have the effect of changing or 
             influencing the control of the issuer of such 
             securities and were not acquired in connection 
             with or as a participant in any transaction having 
             such purposes or effect.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and 
belief, I certify that the information set forth in this 
statement is true, complete and correct.

Date:   February  9, 1994

MELLON BANK CORPORATION                           


By /s/ Michael E. Bleier
   Michael E. Bleier
   General Counsel
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                           EXHIBIT I



The shares reported on the attached Form 13G are held by the 
following Subsidiaries of Mellon Bank Corporation (including 
but not limited to the Subsidiaries of The Boston Company, 
Inc.) as marked (X):


(A)     (X)  Boston Safe Deposit and Trust Company
             Boston Safe Deposit and Trust Company of California
             Boston Safe Deposit and Trust Company of New York
        (X)  Mellon Bank, N.A.
             Mellon Bank (Delaware) National Association
             Mellon Bank (MD)


(B)     (X)  Franklin Portfolio
             Laurel Capital Advisors
        (X)  Mellon Capital Management Corporation
        (X)  Mellon Equity Associates
             The Boston Company Advisors, Inc.
             The Boston Company Financial Strategies, Inc.
        (X)  The Boston Company Institutional Investors, Inc.









        The Item 3 classification of each of the subsidiaries 
listed under (A) above is "Item 3(b) Bank as defined in Section 
3(a)(6) of the Act."


        The Item 3 classification of each of the subsidiaries 
listed under (B) above is "Item 3 (e) Investment Advisor 
registered under Section 203 of the Investment Advisers Act of 
1940."














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<PAGE>


                           EXHIBIT II



(A)     Mellon Bank, N.A. is the trustee of the issuer's 
employee benefit plan (the "Plan") which is subject to ERISA.  
The securities reported include all shares held of record by 
Mellon Bank, N.A. as trustee of the Plan.  The reporting 
person, however, disclaims beneficial ownership of all shares 
that have been allocated to the individual accounts of employee 
participants in the Plan for which directions have been 
received and followed.



(B)     This number includes securities not outstanding which 
are subject to options, warrants, rights or conversion 
privileges that are exercisable within 60 days.



(C)     The filing of this Schedule 13G shall not be construed 
as an admission that Mellon Bank Corporation, or its 
subsidiaries and affiliates, including Mellon Bank, N.A., are, 
for the purposes of this Section 13(d) or 13(g) of the Act, the 
beneficial owners of any securities covered by this Schedule 
13G.






























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<PAGE>



                          EXHIBIT III

                               to

                          SCHEDULE 13G

                           under the

                Securities Exchange Act of 1934



The Boston Company, Inc. and its various subsidiaries 
(collectively referred to as "TBC"), One Boston Place, Boston, 
Massachusetts hereby disclaim beneficial ownership of the 
securities referred to in the Schedule 13G to which this 
Exhibit is attached, and the filing of this Schedule 13G shall 
not be construed as an admission that TBC is, for the purpose 
of Section 13(d) or 13(g) of the Securities Exchange Act of 
1934, the beneficial owner of any securities covered by this 
Schedule 13G.

Pursuant to Rule 13d-1(f)(1) and subject to the proceeding 
disclaimer, TBC affirms it is individually eligible to use 
Schedule 123G and agrees that this Schedule is filed on its 
behalf, and authorizes the General Counsel, any Assistant 
General Counsel and any Associate Counsel of Mellon Bank 
Corporation, each with power to act singly, to file and sign 
this statement on behalf of TBC.




                                 THE BOSTON COMPANY, INC.



                                 By:/s/Charles C. Cutrell, III 
                                 Name: Charles C. Cutrell, III
                                 Title: Counsel







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