The Sensex at the Bombaystock Exchange rose 46 points, or 0.2 per cent, to 19,730 in early trade, today, on the back of sustained buying by funds and retail investors. But later, after swinging between gains and losses, the Sensex stood just 3 points in the positive zone, at 19,686 in afternoon deals, a short while ago. The Sensex had gained over 800 points in the previous four trading sessions.Key stock indices in Japan, China, Hong Kong, Singapore, Taiwan, Indonesia, and South Korea were trading mixed, today.