Traders said the Fed moved to prop up the dollar.

The Federal Reserve bought about $40 million to $50 million by selling Japanese yen when the U.S. currency fell to the 168.70-yen level in New York, several traders reported. The traders said they assumed that the Fed intervened on behalf of the Bank of Japan. Traders in Tokyo also said the Japanese central bank intervened in that market, buying a reported $40 million.