Banc-America Robertson Stephens & Co. said it faces a possible $5 billion judgment in a class action that alleges the brokerage colluded with other firms to rig stock prices.

The San Francisco-based brokerage, a BankAmerica Corp. unit, is the lone holdout from a landmark $1.01 billion settlement between 36 brokerages and investors who filed the suit. The complaint accuses the 37 firms of keeping trading spreads-the difference between the buying and selling price- artificially wide on 1,659 Nasdaq stocks between 1989 and 1994.

Dana Welch, general counsel of the company's Robertson Stephens division, said last week that the company intends to contest the charges in federal court in New York.

"We haven't seen one fact indicating that we did anything wrong, or that any of our personnel did anything wrong," Ms. Welch said. A $5 billion judgment, while possible, is "highly unlikely" because the facts are in the company's favor, she said. Robertson Stephens rejected a $15 million settlement offer, Ms. Welch said.

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