OM Group Inc. agreed to pay $82.5 million to settle a class-action shareholder lawsuit alleging securities fraud relating to a failure by the metals producer to write down the value of its cobalt inventory, according to the suit. The lead plaintiff was the $3 billion Policemen and Firemen Retirement System of the City of Detroit. Payment will be in cash and $8.5 million in shares of unrestricted stock, according to a statement from OMG. The case was filed in November 2002 in U.S. District Court in Ohio. The case against Ernst & Young, OMG's auditors at the time, continues and will be tried Nov. 15, according to a statement from Bernstein Litowitz Berger & Grossmann, attorneys for the Detroit fund.