Rising for the fourth consecutive session, the Sensex at the Bombay Stock Exchange closed a modest 43 points, or 0.2 percent higher, at 18,490, on Thursday, amid easing food inflation, and firm global markets. The Sensex has already rallied more than 820 points in the last three trading sessions. The Nifty at the National Stock Exchange rose 14 points, or 0.3 percent, to 5,536.Stock markets in Japan, Hong Kong, South Korea and Singapore gained between 0.3 percent and 2 percent.