Bond insurer Ambac Financial Group ($0.00 0%) senior vice president and chief financial officer Sean Leonard resigned this week after the company warned it may file for bankruptcy.

Until a replacement is named, his department heads will report to CEO David Wallis, Ambac said in a statement Tuesday.

"Sean’s experience, intelligence and dedication have had a strong and positive impact on the Company," Wallis said. "We are fortunate to have had him as part of the executive team and he will be greatly missed.”

Leonard's resignation -- effective immediately -- comes after Ambac warned in a regulatory filing that it may need to file for bankruptcy protection. In the Securities and Exchange Commission (SEC) filing, Ambac said the $164.7m it holds in cash, short-term investments and bonds is sufficient liquidity to last it until Q211, but acknowledged that it was not a guarantee and it might run out before then.

Ambac posted net income of $2.2bn, or $7.58 per share, in Q309, compared with a net loss of $2.4bn in the year-ago quarter. Quarterly results were impacted by unrealized mark-to-market gains in the New York City-based financial services and insurance firm’s credit derivatives portfolio and gains from Q309 reinsurance cancellations.

Write to Diana Golobay.