The Sensex at the Bombay Stock Exchange gained 134 points, or 0.7 per cent, to 18,628 within the first few minutes of trade, today, on renewed buying by investors. But the Sensex later surrendered all its early gains, and stood 74 points, or 0.4 percent in negative territory, at 18,420, in afternoon trade, a short while ago. Other Asian markets in Japan, China, Hong Kong, Indonesia, Singapore, South Korea and Taiwan were trading mixed, today. Wall Street's Dow Jones Industrial Average had dropped 0.3 per cent, overnight.