Snapping a five-session winning streak, the Sensex at the Bombay Stock Exchange declined 55 points, or 0.3 percent, to 17,691, today, amid profit-booking , and weak global bourses. The Nifty at the National Stock Exchange fell 14 points, or 0.3 percent, to 5,308. Stock markets in China, Hong Kong, Singapore and South Korea fell between 0.2 percent and 2 percent.