Bombay: Stock Exchange benchmark Sensex lost over 486 points in opening trade today. The sensex was trading 17,922, down by over 516 points a short while ago. Brokers said the fall in sensex is due to after the Japanese Nikkei tumbled by over 10 per cent amid fears of a meltdown at a nuclear power plant. They added overnight losses in the US market also dampened the sentiment. Japan’s Nikkei was down by 10.11 per cent, while Hong Kong’s Hang Seng was down 3.88 per cent in morning trade today. The US’s Dow Jones Industrial Average ended 0.43 per cent down in yesterday’s session.