Posting its eighth straight session of gains, the Sensex at the Bombay Stock Exchange shot up 443 points, or 2.5 percent, to close at 18,464, today. The Nifty at the National Stock Exchange spurted 142 points, or 2.6 percent, to 5,578. Stocks rose following the government's action on diesel prices, designed to bring down its burgeoning fiscal deficit and curb under-recoveries of public sector oil marketing companies, and in line with rising global markets.Stock markets in Japan, China, Hong Kong, South Korea and Singapore gained between 0.6 percent and 2.9 percent, after the U.S. central bank announced a new stimulus plan to revive economic growth.