Extending its gains for the sixth straight session, the Sensex at the Bombay Stock Exchange jumped 152 points, or 0.8 percent, to 18,846, today, amid a sharp fall in food inflation, easing concerns over the Greek debt crisis, and firm global markets. The Sensex has now gained almost 1,300 points in just six trading sessions. The Nifty at the National Stock Exchange advanced 47 points, or 0.8 percent, to 5,647.Stock markets in Japan, China, Hong Kong, South Korea, and Singapore rose between 0.3 percent and 1.5 percent.