Remaining firm in afternoon trade, the Sensex at the Bombay Stock Exchange stood 147 points, or 0.7 percent in positive territory, at 21,180 a short while ago. Earlier in the morning, the Sensex had gained 123 points, or 0.6 percent, to 21,156, on buying by funds and retail investors, amid firm Asian bourses. Shares of state-owned, Coal India were in demand after the company announced an interim dividend of 29 rupees per share. Stock markets in Japan, Hong Kong, Indonesia, Singapore, South Korea and Taiwan had gained between 0.4 percent and 2.5 percent, today, on optimism that the global economy is strengthening.The US Dow Jones Industrial Average haed ended 0.7 per cent higher in yesterday's trade.