The BSE benchmark index Sensex regained the 18,000 level today, after rising nearly 209 points in opening trade.The rise was attributed to sustained buying by funds and retailers on better-than-expected quarterly earnings by corporates.The 30-share index, which had gained almost 100 points in last two trading sessions, shot up by 209 points, or 1.17 per cent, to trade at 18,057, in the first few minutes of trade today.In a similar fashion, the wide-based Nifty of the National Stock Exchange moved up by 60 points, or 1.11 per cent, to 5,476.In Asia, Hong Kong's Hang Seng Index rose by 0.09 per cent, while Japan's Nikkei Index by 1 per cent in early trade. The Dow Jones Industrial Average ended higher by 0.03 per cent yesterday.