Its subsidiaries provide financial guarantee products such as bond insurance to clients in both the public and private sectors globally.

Other investors, including Xerox Corp., Ambac management, and Stephens Inc., an investment banking firm, held the remaining equity.

In 1989, Citibank gained sole ownership of the municipal bond insurer, purchasing the remaining shares it had not already secured from its former partners.

Ambac and other bond guarantors such as MBIA were hit hard by the 2007 subprime mortgage financial crisis and on January 18, 2008, its Fitch credit rating was lowered from AAA (the highest) to AA when its plans to raise two billion dollars in new capital failed.

[10] In early 2008, the spectre of the major bond guarantors failing to be able to pay off insurance claims on a trillion dollars of securities backed by sub-prime mortgages and other securitized debt led to attempts to shore them up with infusions of capital.

[15] On June 8, 2010, Ambac announced that it would likely seek a pre-packaged bankruptcy as it was unable to pay dividends from its bond insurance unit to the holding company.

[21] With the leadership of Mr. LeBlanc, on February 12, 2018, Ambac Assurance's Segregated Account exited rehabilitation through a holistic restructuring transaction and is now paying all claims in full in cash.