The Sensex fell by over 90 points in opening trade today.The 30-share BSE benchmark index, which lost 18.93 points in the previous session, fell further by 90.19 points, or 0.57 per cent, to 15,758.61 in opening trade today. In a similar fashion, the wide-based National Stock Exchange Nifty index declined by 27.85 points, or 0.59 per cent, to 4,719.05.In the Asia region, Hong Kong's Hang Seng index was down by 1.11 per cent, while the Tokyo Stock Exchange was closed. The US Dow Jones Industrial Average ended 0.45 per cent lower in the previous session.