Rising for the third day in a row, the Sensex at the Bombay Stock Exchange gained 131 points, or 0.8 percent, at 17,319, on funds buying in blue-chips, and especially IT stocks, today. The Sensex had gained 57 points in the previous two trading sessions. The Nifty at the National Stock Exchange climbed 39 points, or 0.8 percent, to 5,248. Stock markets in Hong Kong, Singapore and South Korea ended mixed.