NEW YORK ( TheStreet) -- Ambac Financial Group's ( ABK) subsidiary Assurance Corp. has filed with the U.S. Bankruptcy Court in Manhattan to withdraw over $6.1 billion in claims against Lehman Brothers Holdings ( LEHMQ) as part of a legal settlement.

The settlement calls for Ambac and Lehman to release each other from any further liability for derivative transaction disputes related to the Lehman bankruptcy.

"Lehman probably had claims against Ambac because they wrapped their deals," says Ed Grebeck, CEO of Tempus Advisors. "It seems like a quid pro quo, but I'm sure Lehman's claims were nowhere near Ambac's."

The deal still needs to be approved by the bankruptcy court, but has the support of Lehman's unsecured creditors, according to an article by The Wall Street Journal.

Ambac is one of several monoline insurers, along with MBIA ( MBI) that are suing investment banks for losses due to improper due diligence. Ambac has also sued Bank of America ( BAC) for over $16.7 billion of mortgage-backed securities, according to published reports. The insurer is claiming that the Countrywide Financial Corp. unit fraudulently induced Ambac to insure bonds to loans that were not made properly.

"This is likely to be an indicator of how many other legal cases with Ambac are handled by the banks," said Grebeck.

"I don't think you could use it as a barometer because Lehman Brothers is using this as a special situation for settling Lehman's bankruptcy. It wouldn't be same for an ongoing business that has the capital to back it up," argues Jim Ryan, a senior analyst of equity research at Morningstar.

Ambac Financial Group's assets were seized by Wisconsin state regulators announced in March that it may have to eventually file for bankruptcy.

An Ambac spokesperson said there was no comment on the settlement.

--Written by Maria Woehr in New York.

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