The Sensex at the Bombay Stock Exchange gained 32 points, or 0.2 per cent, to 18,742 in early trade, today, on the back of covering-up of short positions by participants, amid the monthly expiry in the derivatives segment. Later, the Sensex remained firm, and stood 59 points, or 0.3 percent in the green, at 18,769 in afternoon deals, a short while ago.Stock markets in China, Japan, South Korea, Hong Kong, and Taiwan were trading mixed, today. Over in the US, the Dow Jones Industrial Average had ended 0.2 per cent lower in yesterday's trade.