Mumbai: Dragged down by a massive sell-off amid huge losses on other Asian bourses, the Bombay Stock Exchange benchmark Sensex fell by over 486 points in opening trade on Tuesday.

The 30-share index, which gained 265.39 points in the previous session, tanked 486.88 points below the psychological 18,000 points level at 17,952.60, with all sectoral indices trading in the negative zone with losses up to 2.73 per cent.

In a similar condition, the wide-based National Stock Exchange Nifty index lost 150.55 points, or 2.79 per cent, to 5,380.95 points.

The trading sentiment on the domestic bourses turned extremely weak large after the Japanese Nikkei tumbled by over 10 per cent amid fears of a meltdown at a nuclear power plant, brokers said.

Overnight losses in the US market also dampened the sentiment, they added.