Falling for the fifth straight session, the Sensex at the Bombay Stock Exchange closed with a small loss of 20 points, or 0.1 percent, at 19,640, today. But the Nifty at the National Stock Exchange managed to gain 2 points, at 5,959.Stock markets in Japan, China, Hong Kong, and Singapore gained between 0.1 percent and 3.8 percent.