A summary of Southern California-related business litigation developments during the past week.

Columbia Savings Sues: Columbia Savings & Loan filed suit Thursday in Superior Court against Merrill Lynch for selling the thrift $20 million in debt obligations from a company that went bankrupt a few weeks later. Columbia bought the “remarketed notes” of Lomas Financial Corp. on Aug. 9, 1989. Within weeks the mortgage company defaulted on its debt and filed for bankruptcy, the suit said. Merrill Lynch had not yet been served with the suit.