The Bombay Stocks exchange benchmark Sensex continued its slide for the fourth straight session and opened 57 points down today. The Sensex was trading at 20,160, down by over 24 points a short while ago. Analysts said the fall in Sensex is on concerns over sharp rise in food inflation and a weak trend on other Asian bourses.Similarly, the wide-based National Stock Exchange Nifty index also moved down by 19 points to 6,028 points.Meanwhile, Hong Kong's Hang Seng index was down by 0.14 per cent, while Japan's Nikkei was trading 0.22 per cent lower in early trade today.In the US, the Dow Jones Industrial Average ended 0.22 points lower in yesterday's trade.