U.S. stocks opened lower after the weekly jobless claims report disappointed investors.

The S&P 500 Index is down 3.14 points, or 0.24 percent, to trade at 1,282.82 at 10:18 a.m.  The Dow Jones Industrial Average has fallen 28.99 points, or 0.25 percent, to trade at 11,726.45.  The Nasdaq Composite dropped 0.15 percent.

At 8:30 a.m., the Department of Labor reported that jobless claims for the week ended January 8 was 445,000, which was worse than the expected 415,000 figure.

The market is also weighed down by Merck (NYSE:MRK), the worst performer on the Dow Jones Industrial Average, which plunged 5.52 percent on troubles regarding studies of its anti-clotting drug vorapaxar.

The market is down despite a successful Portuguese debt auction earlier, which eased European sovereign debt fears.