The Sensex at the Bombay Stock Exchange surged 227 points, or 1.3 percent on fag-end buying interest, to close at 18,438, on Monday. The Nifty, at the National Stock Exchange added 60 points, or 1.1 percent, to 5,519.Asian markets ended mixed on Monday. Japan's Nikkei gained 0.1 percent and China's Shanghai Composite index advanced 1.1 percent. But Hong Kong's Hang Seng and Singapore's Strait Times index lost 0.5 percent each and South Korea's Kospi fell 0.4 percent.