Ambac Financial Group,the troubled bond insurer, filed for Chapter 11 bankruptcy protection, a week after missing an interest payment due on some debt.  In its Chapter 11 petition, Ambac listed several groups of bondholders - all represented by BNY Mellon as trustee - as its largest creditors, with a total of $1.6 billion in claims.  All told, the insurer reported that it had $1.7 billion worth of liabilities.  It isn’t immediately clear whether the company had reached a pact with creditors over a “prepackaged” bankruptcy plan, which would shorten its time in Chapter 11 protection.

The main regulator of Ambac’s operating subsidiary, the Wisconsin insurance commissioner, moved this year to effectively split Ambac in two.  In October, the Wisconsin regulator began a process of “rehabilitation” for the so-called segregated account containing $50 billion worth of policies on mortgage-linked bonds.  The plan prescribes a system of payments for affected customers, who will receive a mix of cash and debt for their policies - all subject to approval by a Wisconsin judge.

Ambac is being advised by the Blackstone Group and the law firm Dewey & LeBoeuf.   [CNBC, 11/1;  NYT Dealbook, 11/8]