The Sensex at the Bombay Stock Exchange gained 128 points, or 0.8 percent, to 15,813, today, on the back of a sharp fall in food inflation, and rising European markets. The Nifty at the National Stock Exchange rose 41 points, or 0.9 percent, to 4,734.But stock markets in Japan , China , Hong Kong , Singapore and South Korea lost between 0.1% and 0.8%.