The Bombay Stock Exchange benchmark Sensex rose by almost 33 points in opening trade today on fresh buying by funds and retail investors in oil and gas and realty sector stocks. However, a weakening trend on other Asian Bourses restricted the gains. The 30-share barometer, which lost over 101 points in yesterday's trade, recovered by 0.17 per cent, to 18,426. in the first few minutes of trade today.In a similar manner, the wide-based National Stock Exchange Nifty index rose by nearly 7 points to 5,533 points. Meanwhile, in the Asian region, Hong Kong's Hang Seng index was down by 0.95 per cent, while Japan's Nikkei shed 0.45 per cent in morning trade today. The US Dow Jones Industrial Average ended 0.18 per cent lower in yesterday's trade.