Snapping a four-day rally, the Sensex at the Bombay Stock Exchange lost 256 points, or 1.4 percent, to 17,714, today, amid concerns about food inflation, and negative global cues. The Nifty at the National Stock Exchange shed 70 points, or 1.3 percent, to 5,304.Stock markets in Japan, China, Hong Kong, and Singapore fell between 0.3 percent and 1 percent.