The Sensex at the Bombay Stock Exchange gained 125 points, or 0.7 per cent, to 17,653, in opening trade, today, on buying by funds, amid rising Asian markets. Remaining firm, the Sensex stood 108 points, or 0.6 percent in the green, at 17,635, a short while ago.The markets in Japan, China, Hong Kong, Indonesia, South Korea, Singapore and Taiwan were up between 1 percent and 1.5 percent.