Also

* Warren Buffett’s Berkshire Hathaway Inc. said Ronald Ferguson, former chief executive of the firm’s General Re unit, was notified that he might be sued by U.S. regulators investigating improper reinsurance accounting.

* Tribune Co., owner of the Los Angeles Times, said Patrick Mullen, president of its broadcasting group, had resigned.

* Beckman Coulter Inc. agreed to buy Diagnostic Systems Laboratories Corp. for about $138 million to add fertility and heart-health tests.