Wiping out all its initial gains, the Sensex at the Bombay Stock Exchange stood 100 points, or 0.6 percent in negative territory, at 16,185, in Thursday afternoon deals, a short while ago, on profit-booking by investors, amid the expiry of the monthly derivatives contracts. Earlier in the morning, however, the Sensex had gained 87 points, or 0.5 per cent, to 16,372, on the back of rising regional bourses. But stock markets in Japan, China, Indonesia, Singapore, Hong Kong and South Korea were up by between 0.2 percent and 2.8 percent, today, after strong US manufacturing data boosted investor sentiment. Across in the US, the Dow Jones Industrial Average had gained 1.3 per cent, overnight.