Mumbai: The BSE benchmark Sensex gained nearly 53 points in opening trade on Wednesday on the back of bargain buying of select stocks by funds and retail investors. In addition, covering-up of pending short positions ahead of tomorrow's monthly expiry in the derivatives segment on the National Stock Exchange, drove up stocks of certain companies. The 30-share index of the Bombay Stock Exchange, which had lost 353.07 points in the previous session, rebounded by 52.93 points, or 0.29 percent, to 18,571.15 with oil and gas, PSUs, power and metal sector stocks staging a moderate recovery. Similarly, the wide-based National Stock Exchange Nifty index moved up by 17.35 points, or 0.31 percent, to 5,591.70 points. Brokers attributed the recovery in opening trade to fresh buying by participants with the scrip looking attractive at current valuations, after yesterday's losses following a sharp hike of 50 basis points in interest rates by the RBI in its first quarter review of the monetary policy for 2011-12. Covering-up of short positions by speculators, in view of tomorrow's monthly expiry in the derivatives segment on the NSE also supported the recovery, they added. Meanwhile, Hong Kong's Hang Seng Index shed 0.03 per cent, while Japan's Nekki was down 0.54 per cent in early trade today. The Dow Jones Industrial Average in the US market ended 0.73 percent lower in yesterday's trade.