Stocks markets in India and across the globe have tumbled. At home, the Sensex at the Bombay Stock Exchange plunged more than 450 points in opening trade, later lost even more ground, and was trading a mammoth 611 points in negative territory at 17,083 a short while ago.The Nifty at the National Stock Exchange plummeted 176 points to 5,156 points.The fall on the domestic bourses, followed the crash in stock markets across the globe. Over in the US, Wall Street had its worst day for almost three years, as shares tumbled on fears about the eurozone debt crisis and US economic recovery. The Dow Jones index closed down more than 4.3 per cent overnight, its biggest single day fall since late 2008. Twon other key Wall Street stock indexes, the S&P 500 and Nasdaq fell about 5 per cent each. Earlier. key Eurpean markets had fallen about 3 per cent. Asian stock markets also slumped today, extending the global equity sell-off. Japan's main Nikkei 225 index shed 3.4 per cent to 9,330. South Korea lost 4.2 per cent while Australia slid 2.4 per cent.