The Bombay Stock Exchange benchmark Sensex on Tuesday opened 56 points down as funds and retail investors booked profits. Sensex was trading at 18267, up by 22 points. Similarly, the wide-based National Stock Exchange index Nifty also moved down by 22 to 5,479 points. Hong Kong's Hang Seng index shed 0.87 per cent, while Japanese Nikkei was up by 0.53 per cent in the morning trade.