At the Bombay Stock Exchange, strong buying interest by investors had lifted the Sensex a hefty 405 points, or 2 percent, to 20,820 in afternoon trade, a short while ago. Earlier, in morning deals, the Sensex had climbed 118 points, or 0.6 percent, to 20,533. The Sensex rose on fresh buying by investors, amid rising regional bourses, and on speculation that the US central bank could maintain its monetary stimulus to the US economy for a longer period. Stock markets in China, Hong Kong, South Korea, Singapore and Taiwan had added between 0.3 percent and 1 percent, today. But Wall Street's Dow Jones Industrial Average had ended flat, yesterday.