Snapping two days of gains, the Sensex at the Bombay Stock Exchange fell 75 points, or 0.5 percent, to 15,739, on profit-booking by investors on Friday.The Nifty at the National Stock Exchange dropped 20 points, or 0.4 percent, to 4,714.But stock markets in China , Hong Kong , Singapore and South Korea rose between 0.4% and 1.4% on encouraging US economic data.