In a special trading session today, the Sensex at the Bombay Stock Exchange rose 53 points or 0.3 percent to close at 17,187.The Nifty at the National Stock Exchange gained 18 points, or 0.4 percent, to 5,209. The special trading session was conducted by both the leading stock exchanges between 11:15 am and 12:45 pm due to the up gradation of their systems.