Mumbai: Failing to sustain Wednesday's gains, the Bombay Stock Exchange benchmark Sensex fell by over 89 points in opening trade on Thursday, after funds and retail investors booked profits, amid a weak trend overseas on worsening European financial crisis.

The 30-share Sensex, which gained 272.60 points in the previous session, fell by 89.41 points, or 0.52 percent, to 17,041.10 in the first few minutes of trade.

In a similar fashion, the wide-based National Stock Exchange Nifty index shed 27.40, or 0.53 percent, to 5,133.60.

Stocks of IT, auto, realty, metals and banking sectors came under selling pressure, which dragged down the Sensex.

Market experts said sentiments turned weak on profit-booking by funds and retail investors on the handsome gains recorded in the previous session and a subdued trend on the other Asian bourses in line with overnight huge sell-off on US markets, amid worries over the economy and Europe's worsening financial crisis.

Meanwhile, in the Asian region, Hong Kong's Hang Seng Index was down 2.52 percent, while Japan's Nikkei lost 1.29 percent in morning trade on Thursday. The Dow Jones Industrial Average in the US fell by 4.62 percent in the previous session on Friday.