The Sensex at the Bombay Stock Exchange fell 18 points, or 0.1 per cent, to 19,965 in early trade, today, as funds and retail investors booked profits, amid falling regional markets. Later, the Sensex lost further ground, and stood 66 points, or 0.3 percent in the red, at 19,921 in afternoon trade, a short while ago. The Sensex had gained over 320 points in the last two trading sessions.Key stock indices in Japan, China, Hong Kong, South Korea, Indonesia and Taiwan had lost between 0.1 percent and 2 pernet, today. While in the US market, the Dow Jones Industrial Average had ended 0.2 per cent higher in yesterday's trade.