The Sensex at the Bombay Stock Exchange opened 57 points, or 0.3 percent higher, at 20,073, this morning, on the back of selective buying by funds and retail investors. But profit-booking soon set in, and the Sensex later surrendered all its early gains, and was trading 24 points, or 0.1 percent in the red, to slip below the 20,000 point mark, at 19,992, a short while ago. Other regional markets in China, Hong Kong, Singapore, Indonesia and South Korea were trading mixed, today. In the US, the Dow Jones Industrial Average had added 0.2 per cent, overnight, on news that the US economy grew at a faster-than-expected 2.6 percent in the third quarter.