The Ambac Financial Group, Inc., generally known as Ambac, is an American holding company. Its subsidiaries provide financial guarantee products such as bond insurance to clients in both the public and private sectors globally. Ambac Assurance is a guarantor of public finance and structured finance obligations. Its common stock and common stock purchase warrants are listed on the NYSE under the symbols AMBC and AMBCW respectively. Ambac is regulated by the insurance commission of Wisconsin. It has its headquarters in Lower Manhattan, New York City. Ambac Financial Group's subsidiaries include Ambac Assurance Corporation and Everspan Financial Insurance Company. Wikipedia