At the forex market, the rupee had tumbled sharply by 47 paise, to 64.73 against the dollar in afternoon trade on Thursday. The rupee slumped as the dollar strengthened against other currencies overseas, after the US Federal Reserve, or central bank, hinted at another interest rate hike by the end of the year.And at the stock markets, after a positive opening, the Sensex at the Bombay Stock Exchange quickly slipped into the red, and had declined 109 points, or 0.3 percent, to 32,291 a short while ago. The Nifty at the National Stock Exchange had dropped 45 points, to 10,096. Other key regional bourses in China, Hong Kong, South Korea and Singapore had posted small losses of upto 0.2 percent.