As the government fights big banks over the financial crisis, plaintiffs lawyers at Quinn Emanuel Urquhart & Sullivan are waging a separate battle — for companies — against financial institutions.

“I view our role in some respect as a supplement to regulators,” said Philippe Selendy, chairman of the securities and structured-finance practice. “The way to achieve the best result is to be prepared for the long haul and have clients understand that you may need to litigate for multiple quarters and possibly years.”

The 200 lawyers who make up the practice have won billions for their clients — including the Federal Housing Finance Agency (FHFA), Assured Guar­anty Municipal Corp. and MBIA Insur­ance Corp. — over the past two years. In 2011, Quinn lawyers, with Kasowitz, Benson, Torres & Friedman, filed more than a dozen complaints against banks and institutions — including JPMorgan Chase & Co. and Goldman Sachs — on behalf of the FHFA. Two of those cases have settled. UBS Americas settled in July for $885 million; the terms of a deal with Citibank remain confidential.

In May 2013, Selendy and partner Adam Abensohn won a $450 million settlement for its client Assured Guaranty against UBS Real Estate Securities Inc. The deal resolved allegations that UBS distorted the risk of residential mortgage-backed securities. “It’s a systematic review of whether defendants spoke honestly and with integrity of the attributes inside the loans,” Selendy said. “There is no question that the nature of the rulings we obtain are broadly of interest to the plaintiffs bar.”

Quinn brings to its cases lawyers who often have experience on the plaintiffs and defense sides, giving the firm a rounded perspective. “If we file in a complaint, we are in it for the long haul until we get a result,” Selendy said.