The Sensex at the Bombay Stock Exchange gained 66 points, or 0.4 per cent, to 18,395 in early trade, today, on select buying by investors. Later, the Sensex remained firm, and stood 64 points, or 0.4 per cent in the green, at 18,393 in afternoon deals, a short while ago.Other Asian markets in China, Singapore, Hong Kong, Japan, Taiwan, South Korea and Indonesia were trading mixed, today. The US Dow Jones Industrial Average had ended 0.1 per cent lower in yesterday's trade.