<PAGE> OMB APPROVAL OMB Number: 3235-0145 Expires: December 31, 1997 Estimated average burden hours per response .... 14.90 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. ___)* AMBAC INC. (Name of Issuer) COMMON STOCK (Title of Class of Securities) 023139108 (CUSIP Number) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).
<PAGE> CUSIP No. 023139108 13G Page 2 of 2 Pages 1 NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON SANFORD C. BERNSTEIN & CO., INC. 767 FIFTH AVENUE NEW YORK NY 10153 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 CITIZENSHIP OR PLACE OF ORGANIZATION 5 SOLE VOTING POWER 1,854,139 NUMBER OF SHARES 6 SHARED VOTING POWER* BENEFICIALLY 344,258 OWNED BY EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON 3,263,994 WITH 8 SHARED DISPOSITIVE POWER 0 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 3,263,994 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES / / 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 9.3% 12 TYPE OF REPORTING PERSON IA/BD * Sanford C. Bernstein & Co., Inc. clients who have appointed an independent voting agent with instructions to vote shares in the same manner as Sanford C. Bernstein & Co., Inc.
<PAGE> Sanford C. Bernstein & Co., Inc. Investment Research and Management One State Street Plaza, New York, N.Y. 10004-1545 212-504-5000 Fax 212-504-5121 Registered Investment Advisor Member, New York Stock Exchange, Inc. SCHEDULE G Under the Securities Exchange Act of 1934 Item 1(a): Ambac Inc. Item 1(b): One State Street Plaza New York NY 10004 Item 2(a): Sanford C. Bernstein & Co., Inc. Item 2(b): 767 Fifth Avenue New York NY 10153 Item 2(c): New York Item 2(d): Common Item 2(e): 023139108 Item 3: Investment Advisor/Broker Dealer Item 4(a): 3,263,994 Item 4(b): 9.3% Item 4(c)(i): 1,854,139 Item 4(c)(ii):* 344,258 Item 4(c)(iii): 3,263,994 Item 4(c)(iv): 0 Item 5: Not Applicable Item 6: The security referred to in this schedule is held for the accounts of discretionary clients. These clients have the right to receive dividends from and the proceeds of the sale of such security. Item 7: Not Applicable Item 8: Not Applicable Item 9: Not Applicable Item 10: 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 purpose or effect. * Sanford C. Bernstein & Co., Inc. clients who have appointed an independent voting agent with instructions to vote shares in the same manner as Sanford C. Bernstein & Co., Inc.
<PAGE> Schedule G Under the Securities Exchange Act of 1934 Page Two 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. 1/30/97 Date /s/ Michael Borgia Signature Michael Borgia, Senior Vice President Name/Title