The Sensex at the Bombay Stock Exchange rose 48 points, or 0.3 per cent, to 18,811 in early trade, this morning, on continued buying by funds and retail investors. But later the Sensex turned volatile, and after swinging between gains and losses, it stood 7 points in negative territory, at 18,756 in afternoon deals, a short while ago. The 30-share Sensex had gained nearly 332 points in the past four trading sessions. Other Asian markets in Hong Kong, Singapore, Japan, China, Indonesia, Taiwan and South Korea were trading mixed, as investors remained cautious ahead of the start of voting in the US presidential elections.