Peat, Marwick, Mitchell & Co. settled a lawsuit.

The Federal Deposit Insurance Corp. and the accounting firm reached a tentative settlement of a $153.4-million lawsuit brought against Peat, Marwick after the collapse of Penn Square Bank, according to attorneys in the case. Both sides declined to discuss terms of the settlement. The FDIC said it could not discuss the settlement because Peat, Marwick was the defendant in five additional suits set for a consolidated trial scheduled for Aug. 18 in Oklahoma City. In the lawsuit against Peat, Marwick, the FDIC contended that the accounting firm failed to point out the bank’s financial problems after audits in 1981 and 1982.