FORM 4	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549	OMB APPROVAL
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).	STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940	OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response. . .0.5 Filed By Romeo and Dye's Section 16 Filer www.section16.net

1. Name and Address of Reporting Person* Lassiter Phillip B.	2. Issuer Name and Ticker or Trading Symbol Ambac Financial Group, Inc. - "ABK"		6. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director                                       10% Owner X Officer (give title below)          Other (specify below) Chairman and Chief Executive Officer
(Last)      (First)     (Middle) Ambac Financial Group, Inc. One State Street Plaza	3. I.R.S. Identification Number of Reporting Person, if an entity (voluntary)	4. Statement for Month/Day/Year February 28, 2003
(Street) New York, NY 10004		5. If Amendment, Date of Original (Month/Day/Year)	7. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person     Form filed by More than One Reporting Person
(City)     (State)     (Zip)	Table I — Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1. Title of Security (Instr. 3)	2. Trans- action Date (Month/ Day/ Year)	2A. Deemed Execution Date, if any (Month/Day/ Year)	3. Trans- action Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 & 5)			5. Amount of Securities Beneficially Owned Follow- ing Reported Transactions(s) (Instr. 3 & 4)	6. Owner- ship Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/28/03		F		38,734(1)	D	$48.67
Common Stock	02/28/03		M		51,851(2)	A	$36.35
Common Stock	02/28/03		F		39,916(3)	D	$48.67
Common Stock	02/28/03		M		53,433(4)	A	$36.35	1,209,783	D
Common Stock	02/28/03							2,715(5)	I	Savings Plan Trust(6)
Common Stock								12,000	I	By Spouse

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number

FORM 4 (continued) Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conver- sion or Exercise Price of Derivative Security

3. Trans- action Date (Month/ Day/ Year)

3A. Deemed Execution Date, if any (Month/ Day/ Year)

4. Trans- action Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 & 5)

6. Date Exercisable and Expiration Date (Month/Day/ Year)

7. Title and Amount of Underlying Securities (Instr. 3 & 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Owner- ship Form of Deriv- ative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exer-cisable

Expira- tion Date

Title

Amount or Number of Shares

Employee Stock Option (Right to Buy)

$36.35

02/28/03

M

51,851

08/05/00

03/03/03

Common Stock

51,851

0

D

Employee Stock Option (Right to Buy)

$36.35

02/28/03

M

53,443

08/05/00

03/03/03

Common Stock

53,443

0

D

Explanation of Responses:

(1) Shares were used to pay for the option price of the shares acquired upon exercise of the employee's stock options.
(2) Issuance of shares in excess of shares tendered to pay the exercise price of options was made in the form of Restricted Stock Units (total of 13,117) which vest immediately and will be settled one year after the Reporting Person's retirement date.
(3) Shares were used to pay the option price of the shares acquired upon exercise of the employee's stock options.
(4) Issuance of shares in excess of shares tendered to pay the exercise price of options was made in the form of Restricted Stock Units (total of 13,517) which vest immediately and will be settled one year after the Reporting Person's retirement date.
(5) Represents shares beneficially owned as of February 28, 2003.
(6) Based on a plan statement as of February 28, 2003.

By: /s/ Anne G. Gill, Attorney-in-fact for Phillip B. Lassiter
              
**Signature of Reporting Person 03/04/2003
Date

**Intentional misstatements or omissions of facts constitute Federal Criminal Violations.
See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed.
          If space is insufficient, See Instruction 6 for procedure.

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

POWER OF ATTORNEY





   I, PHILLIP B. LASSITER, do hereby nominate, constitute and appoint

each of Anne G. Gill, Gregg L. Bienstock and Patricia Lo Cascio, as my true and lawful

agent and attorney-in-fact, with full power and authority to act hereunder, in his or her

discretion, in my name and on my behalf as fully as I could if I were present and acting in

person, to make any and all required or voluntary filings under Section 16(a) of the

Securities Exchange Act of 1934, as amended (the "Exchange Act"), and the applicable

rules and regulations thereunder, with the Securities and Exchange Commission, the New

York Stock Exchange, Ambac Financial Group, Inc., a Delaware corporation (the

"Company"), and any other person or entity to which such filings may be required under

Section 16(a) of the Exchange Act as a result of my service as an officer of the Company or

beneficial ownership (within the meaning of Section 16(a) of the Exchange Act) of more

than ten percent of any class of equity securities of the Company.



   I hereby consent to, ratify and confirm all that each said attorney-in-fact

shall do or cause to be done by virtue of this Power of Attorney.  I hereby acknowledge that

each attorney-in-fact, in serving in such capacity at my request, is not assuming, nor is the

Company assuming, any of my responsibilities to comply with Section 16 of the Exchange

Act.



   This Power of Attorney shall remain in full force and effect from this date

forward for so long as I am an officer or director of the Company and for such time

thereafter as may be necessary to make any such filings or until revoked or modified by me.

I hereby revoke all prior powers of attorney relating to the foregoing acts.



   IN WITNESS WHEREOF, I have hereunto signed my name this 22nd day

of October, 2002.


 /s/ Phillip B. Lassiter
__________________________

PHILLIP B. LASSITER