Maintaining the downward trend, the Sensex at the Bombay Stock Exchange was trading 22 points in the negative territory at 17,686, when reports last came in.The 30-share index lost over 78 points in opening trade today. The fall in the Sensex was attributed to fresh selling by funds, amid a weakening trend on other Asian bourses.In a similar fashion, the wide-based Nifty of the National Stock Exchange was trading 2 points in the red at 5,367.In the Asia region, Hong Kong's Hang Seng index was down by 1.08 per cent and Japan's Nikkei index shed 0.56 per cent in morning trade today.