The Sensex at the Bombay Stock Exchange climbed 79 points, or 0.4 per cent, to 18,216 in opening trade, today, on emergence of selective buying by investors, amid a firm trend on the other Asian bourses. But the Sensex later gave up all its initial gains, and stood 48 points, or 0.3 percent in negative territory, at 18,089, in afternoon trade, a short while ago. The 30-share Sensex has lost almost 400 points in the last two trading sessions. But stock markets in Japan, China, South Korea, Taiwan, Hong Kong, Singapore and Indonesia were up by between 0.2 percent and 1.5 percent, today. In the US, the Dow Jones Industrial Average had ended 0.6 per cent lower, overnight.