The Sensex at the Bombay Stock Exchange fell 20 points, or 0.1 percent, to 17,484 in morning trade, today, on mild profit- booking by investors, amid weak global bourses. Later, the Sensex remained slightly weak, and stood 40 points, or 0.2 percent in negative territory, at 17,464 in afternoon trade, a short while ago. The Sensex had gained over 400 points in the past four trading sessions.Key stock indices in Japan, Hong Kong, Singapore, South Korea and Taiwan were down by between 0.2 percent and 1.2 percent, today, after disappointing US economic data reignited fears about the strength of economic recovery, and on renewed concerns about the euro zone debt crisis. Over on Wall Street, the Dow Jones industrial average had fallen 0.5 percent, overnight.Meanwhile, at the interbank foreign exchange market, the rupee strengthened 7 paise, to 52.07 against the dollar.