The Sensex at the Bombay Stock Exchange closed with a modest gain of 30 points, or 0.2 percent, at 18,470, after volatile trade, today, amid easing crude oil prices, and firm Asian markets. The Nifty at the National Stock Exchange rose 10 points, or 0.2 percent, to 5,531. Stock markets in Japan, China, Hong Kong, and South Korea rose between 0.1 percent and 0.6 percent.