Rising for the third straight session, the Sensex at the Bombay Stock Exchange gained 39 points, or 0.2 percent, to close at 18,558,on Monday, on hopes of higher capital inflows. The Sensex had gained over 610 points in the last two trading sessions. The Nifty at the National Stock Exchange advanced 5 points, or 0.1 percent, to 5,477.Stock markets in Japan, China, Hong Kong South Korea and Singapore ended mixed.