Ending its six-day string of losses, the Sensex at the Bombay Stock Exchange closed with a modest gain of 30 points, or 0.2 percent, at 18,339, amid rising Asian and European markets, today. But the Nifty at the National Stock Exchange extended its losses for the seventh straight day, as it fell 3 points, to 5,571.Stock markets in Japan, China, Hong Kong, South Korea and Singapore rose between 0.1 percent and 1.5 percent.