The Sensex at the Bombay Stock Exchange rose 63 points, or 0.4 per cent, to regain the psychological 18,000 point mark, at 18,003 in early trade, today, on selective buying by investors at attractive low levels. But later, after swinging between negative and positive territory, in volatile trade, the Sensex stood a marginal 2 points in the positive zone, at 17,943, a short while ago. Other Asian markets in South Korea, Singapore, Indonesia Hong Kong and Taiwan were down by between 0.1 percent and 1 percent, today, on worries about a slowdown in the global economy.