The Sensex at the Bombay Stock Exchange gained 53 points, or 0.3 per cent, to 19,132 in opening trade, this morning, on renewed buying by investors, amid positive regional bourses. But the Sensex later surrendered all its initial gains, on profit-booking after a recent strong rally, and stood a modest 36 points, or 0.2 percent in negative territory, at 19,042, in afternoon deals, a short while ago.Other markets in Japan, Hong Kong, Indonesia and Singapore were up by between 0.5 percent and 1.4 percent, today. The US Dow Jones Industrial Average had ended 0.7 per cent higher.