The BSE benchmark Sensex lost over 88 points to trade below 18,000 mark in opening trade Wednesday on fresh selling by funds and retail investors. The 30-share barometer fell to 17,924 points in the first few minutes of trade as realty, IT and oil and gas company stocks retreated. The wide-based National Stock Exchange Nifty index moved down by 22 points to 5,373 points. Brokers attributed the downslide on the bourses to selling by funds and retail investors in tandem with a weakening trend on other Asian bourses following overnight losses in the US market after data showed the market for new homes remained weak. Hong Kong's Hang Seng index was trading lower by 0.69 per cent, while Japan's Nikkei was marginally up in morning trade on Wednesday. In the US, the Dow Jones Industrial Average ended down by 0.20 per cent in yesterday's trade.