The Bombay Stock Exchange benchmark Sensex fell by 93 points in opening trade today on profit booking amid weak trend. The Sensex was trading at 19,821, down by over 108 points a short while ago.In other Asian markets, the Hong Kong's Hang Seng index was quoting lower by 1.04 per cent, while Japanese Nikkei was marginally up by 0.61 per cent in the morning trade today.In the US, Dow Jones Industrial Average ended 1.57 per cent higher.