Worries have focused on the health of European banks, particularly those in France, this week. France's central bank said Thursday that the country's banks are solid and blamed "unfounded rumors" for big drops in their stocks. The French CAC 40 stock index fell 3.3 percent.
Investors worry that Europe's debt problems could hurt the banks that own European government bonds. Because of how intertwined the global financial system is, pain for European banks could lead to more trouble for the U.S. banking industry and economy.
Ninety minutes ahead of the opening, Dow Jones industrial average futures fell 95 points, or 0.9 percent, to 10,630. S&P 500 index futures fell 12.30, or 1.2 percent, to 1,111.20.Nasdaq 100 futures fell 9, or 0.4 percent, to 2,076. Stock futures don't always accurately predict how markets will open.
U.S. stock futures had been solidly higher earlier in the morning, and are not always a reliable indicator of how the market will open.
Cisco Systems Inc., considered a bellwether for the technology industry, reported profit for its latest quarter that topped analysts' expectations. It also said revenue may grow more quickly this quarter than analysts were anticipating. Cisco rose 12.2 percent in premarket trading.
News Corp., the media conglomerate that owns Fox News, rose 4.2 percent ahead of the bell. It also reported earnings late Wednesday that were better than analysts expected.
The Dow on Wednesday plunged 519.83 points on worries about Europe's debt problems and the weak economy. It was the third straight day that the Dow moved more than 400 points, either up or down. That hasn't happened since November 2008.