X0101 42003-05-20 0000874501 AMBAC FINANCIAL GROUP INC ABK 0001216276 PFEFFER HOWARD C 0100Senior Managing DirectorCommon Stock2003-05-204F0555760.12D29599DCommon Stock2003-05-204M01100030.38A40599DEmployee Stock Option (Right to Buy)30.382003-05-204M0110000D2000-01-272005-01-27Common Stock110007000DEmployee Stock Option (Right to Buy)60.122003-05-204A055570A2004-05-202005-01-27Common Stock55575557DShares were used to pay the option exercise price of shares upon exercise of the employee stock options.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 5,543) which vested immediately and will be settled upon termination.Based on plan statement, as of April 30, 2003, 6,240 shares were indirectly owned by the Reporting Person through Ambac's Savings Plan Trust.Exercisable as follows: 6,000 shares on 01/27/1999; an additional 6,000 shares on 01/27/2000; and an additional 6,000 shares on 01/27/2001.Anne G. Gill, Attorney-in-fact for Howard C. Peffer2003-05-21