The Sensex at the Bombay Stock Exchange, which had opened 209 points higher, this morning, later rallied even more strongly, to gain a huge 500 points, or 2.8 percent, and regain the key 18,000 mark, at 18,323, in afternoon deals, a short while ago. The Sensex rose as investors, encouraged by budgetary proposals, such as the cut in surcharge on corporate tax, went on a buying spree. Strong infrastructure sector growth numbers for January, and firm global bourses also helped lift the domestic markets. The Sensex has already gained nearly 200 points in the past two trading sessions. Regional markets in Japan, China, Indonesia, Singapore and Taiwan were up by between 0.2 percent and 1.5 percent, today. Over in the US, the Dow Jones Industrial Average had ended 0.8 per cent higher, overnight, on optimistic remarks from influential investor, Warren Buffett, and positive economic data.