U.S. stock futures are down sharply ahead of the market open Thursday after worries emerged about the financial stability of one of Portugal's largest financial firms. Those concerns hit European stock and bond markets.

KEEPING SCORE: Dow Jones industrial average futures fell 179 points, or 1.1 percent, to 16,734 as of 9:04 a.m. Eastern time. Standard & Poor's 500 index futures slid 20 points, or 1 percent, to 1,946, while Nasdaq 100 futures are down 47 points, or 1.2 percent, to 3,838. The S&P 500 posted a modest gain Wednesday, after Alcoa turned in solid results to kick off the second-quarter earnings season. The benchmark stock index is still down 0.6. percent this week, pulling back from the record high reached last Thursday.

PORTUGAL WORRIES: Espirito Santo Financial Group suspended trading in its shares Thursday as it addressed accounting irregularities at Espirito Santo International, its largest shareholder. Espirito Santo Financial Group is, in turn, the largest shareholder in Banco Espirito Santo, Portugal's largest bank. The bank's share price fell sharply in morning trading. The government insists the bank is solid. The market turmoil was an unwelcome relapse into investor uncertainty for Portugal, which concluded its three-year international bailout program in May. Portugal needed a 78 billion-euro ($106 billion) rescue in 2011 during the eurozone's debt crisis.

EUROPE: Major stock indexes tumbled in Germany and France. Both the DAX in Frankfurt and the CAC-40 in Paris slumped 1.9 percent. Britain's FTSE 100 index sank 1.1 percent.

US JOBS: Applications for US unemployment benefits sank last week. The Labor Department said weekly applications for unemployment benefits dropped to 304,000. The four-week average, a less volatile measure, dipped 3,500 to 311,500, the second-lowest reading since August 2007.

BONDS: In the market for U.S. government debt, the yield on the 10-year Treasury note dropped to 2.51 percent, down from 2.55 percent late Wednesday. Bond yields fall when prices rise.