The yen has fallen despite the Bank of Japan raising interest rates in recent years - structuresxx/iStockThe Japanese yen has suffered its sharpest sell-off since February as an American attempt to prop up the ailing currency unravels. The decline will add to pressure on the Bank of Japan to raise interest rates to support its currency. The yen has fallen despite the Bank of Japan raising interest rates in recent years. Speculators cut their bets on declines in the Japanese yen by the most in more than 12 years, according to data from the Commodity Futures Trading Commission released on Friday. Claudio Irigoyen, a global economist at Bank of America, warned the intervention would raise pressure on the Bank of Japan to raise rates further.