Falling for the fourth straight session, the Sensex at the Bombay Stock Exchange declined 110 points, or 0.6 percent, to 17,103, today, on worries about the monsoon and rising food prices. The Sensex had lost 405 points in the previous three trading sessions. The Nifty at the National Stock Exchange shed 30 points, or 0.6 percent, to 5,197. Stock markets in Hong Kong, South Korea and Singapore posted small gains of between 0.1 percent and 0.3 percent.