The Sensex at the Bombay Stock Exchange rose 27 points, or 0.1 per cent, to 18,534 in opening trade on Tuesday morning, on bargain-hunting by investors, despite a weak trend on the other regional bourses. Later, the Sensex slipped slightly into negative territory, but then recovered strongly, to stand a good 158 points, or 0.9 percent in the positive zone, at 18,665 in volatile trade, a short while ago. The Sensex had lost more than 110 points in the past two trading sessions. Stock markets in Japan, China, Hong Kong, Indonesia, Singapore, South Korea and Taiwan were down by between 0.1 percent and 0.8 percent, today, as worries about the US and European debt problems weighed on sentiment. In the US, the Dow Jones Industrial Average had ended 0.8 per cent lower, overnight.