NEW YORK (Reuters) - A federal judge in Manhattan on Thursday dismissed a lawsuit by investors that accused nine large banks, including six from Canada, of conspiring to manipulate a Canadian rate benchmark to improve profits from derivatives trading.

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U.S. District Judge Analisa Torres rejected racketeering and antitrust claims by the lead plaintiff, the Fire & Police Pension Association of Colorado, against Royal Bank of Canada, Toronto-Dominion Bank, Bank of Nova Scotia and other banks.

Lawyers for the plaintiff did not immediately respond to requests for comment.

The proposed class action concerned the alleged suppression from August 2007 to June 2014 of the Canadian Dealer Offered Rate (CDOR), a rate at which banks would lend to corporate clients using bankers’ acceptances, a short-term credit instrument.

CDOR, now called the Canadian Dollar Offered Rate, is calculated daily by Thomson Reuters based on rate submissions from banks.

The plaintiff accused banks of manipulating CDOR to reduce interest owed to investors on CDOR-based derivatives transactions in the United States, including swaps and Canadian dollar futures contracts, and boost profit.

But the judge said the alleged wrongful conduct occurred in Canada, which is not covered by the U.S. anti-racketeering law known as RICO, and the plaintiff failed to show that any rigging left it worse off.

Torres also found no proof of a common profit motive among banks to suppress CDOR because they held more CDOR-based derivative contracts, under which they made interest payments, than CDOR-based loans, on which they received interest payments.

Other defendants included Bank of Montreal, Canadian Imperial Bank of Commerce, National Bank of Canada, Bank of America Corp, Deutsche Bank AG and HSBC Holdings Plc.

Canadian regulators updated the CDOR-setting process after the Investment Industry Regulatory Organization of Canada in January 2013 identified “potential” for manipulation.

The case is Fire & Police Pension Association of Colorado v Bank of Montreal et al, U.S. District Court, Southern District of New York, No. 18-00342.