Lifted by rising global markets, the Sensex at the Bombay Stock Exchange zoomed a massive 591 points, or 3.7 per cent, to 16,714 within minutes of opening, this morning.Later, after paring its gains somewhat, the Sensex still stood a hefty 457 points, or 2.8 percent in positive territory, at 16,581 in afternoon deals, a short while ago.Other key stock indices in Japan, China, Hong Kong, Indonesia, Singapore, South Korea and Taiwan were up by between 1.9 percent and 5.5 percent, today.Stocks rose after the world's six major central banks took action to boost liquidity in the global financial system. Over in the US, the Dow Jones Industrial Average had shot up 4.2 per cent, overnight.