Erasing all its early losses, the Sensex at the Bombay Stock Exchange ended with a slim gain of 22 points, or 0.1 percent, at 18,618, after volatile trade, on Thursday. The Nifty at the National Stock Exchange rose 14 points, or 0.3 percent, to 5,600.Stock markets in Japan, China, Hong Kong, South Korea, and Singapore ended mixed.