Stocks fell on Thursday after weaker-than-expected retail sales and as the European Central Bank stopped short of taking any additional measures to keep a debt crisis from spreading in the euro zone.

Most top retail chains reported weaker-than-expected same-store sales for April, sparking concerns about the health of consumer spending.

The reports raised the question whether the consumer was showing signs of fatigue or whether an early Easter had distorted the figures by taking a bite out of April's sales, Craig Peckham, equity trading strategist at Jefferies & Company in New York, said.

Given the deteriorating sentiment from a risk standpoint, it seems as though equity investors are taking a more negative view of something fundamental in here, said Peckham.

The Dow Jones industrial average <.DJI> fell 99.61 points, or 0.92 percent, to 10,768.51. The Standard & Poor's 500 Index <.SPX> lost 13.86 points, or 1.19 percent, to 1,152.04. The Nasdaq Composite Index <.IXIC> gave up 30.99 points, or 1.29 percent, at 2,371.30.

Weak results hit shares including Costco Wholesale Corp , which fell 2.9 percent to $58.60, while Gap Inc was down 4 percent at $23.69.

Fears Greece's debt crisis could spread to other euro zone nations with heavy debt loads kept an underlying negative tone in the market. Investors were disappointed the ECB did not discuss the outright purchases of European sovereign debt as some had hoped for, while the ECB left interest rates at a record low.

There's just a state of unease that continues to get worse seemingly by the day as the contagion fear really becomes more acute, said Peckham.

Economic data was mixed as productivity grew solidly in the first quarter but the number of workers filing claims for jobless aid fell less than expected last week.

(Editing by Kenneth Barry)