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NEW YORK (Reuters) - A U.S. judge on Thursday dismissed a lawsuit against 16 big banks by retail foreign currency investors who claimed they were indirectly harmed by a conspiracy to rig prices.

U.S. District Judge Lorna Schofield in Manhattan said the investors failed to show they had legal standing to pursue antitrust claims, or that the banks’ alleged conspiracy in the $5.1-trillion-a-day currency market was the proximate cause of their losses.

The plaintiffs claimed they were injured by having bought currencies from dealers that did not rig prices, but which passed on the costs of the conspiracy. They said the conspiracy included the defendants’ alleged use of chat rooms with such names as “The Cartel” and “The Mafia.”

A lawyer for the plaintiffs did not immediately respond to a request for comment.

Fifteen of the 16 banks have settled similar litigation by other investors for $2.31 billion, with Credit Suisse Group AG CSGN.S being the holdout, court papers show.

Bank of America Corp BAC.N, Barclays Plc BARC.L, Citigroup Inc C.N, Goldman Sachs Group Inc GS.N, JPMorgan Chase & Co JPM.N, Royal Bank of Canada RY.TO and Royal Bank of Scotland Group Plc RBS.L are among the settling banks. All were defendants in the lawsuit dismissed by Schofield.