The Sensex at the Bombay Stock Exchange gained 158 points, or 0.8 percent, to close at 18,947, on Monday, amid encouraging trade data, hopes of more steps by the government to support the rupee, and rising regional markets. The Nifty at the National Stock Exchange climbed 47 points, or 0.8 percent, to 5,612.Stock markets in China, Hong Kong, South Korea and Singapore rose between 0.1 percent and 2.4 percent.