Many companies are reporting weaker-than-expected revenues for the first quarter, and some are placing the blame on Europe’s weak economy.

So far, just more than one-third of companies in the Standard & Poor’s 500 Index have released their quarterly results. While 68 percent of them have beaten analysts’ forecasts for earnings per share, only 40 percent have exceeded revenue predictions, according to Thomson Reuters data cited by CNBC.

That’s far below the average 62 percent that have historically outdone revenue projections.

Editor's Note: The ‘Unthinkable’ Could Happen — Wall Street Journal. Prepare for Meltdown

"When you have over half the revenues on the S&P 500 companies coming from overseas, you need stability in Europe and some better growth in China," Scott Wren, senior equity strategist at Wells Fargo Advisors, told CNBC.

Among those companies reporting corporate troubles in Europe were Ford Motor, which reported a $462 million loss in the region, and Whirlpool and Owens-Illinois, both of which suffered sales decreases in Europe.

"Companies continue to have an unrelenting focus on being efficient," Matt Kaufler, portfolio manager of the Federated Clover Fund, told CNBC. "It will continue to be a tough revenue environment for the next quarter, and earnings expectations for the year will be pulled in a bit."

Europe’s economy doesn’t show much sign of recovery yet, which could mean continued bad news for U.S. sales.

Markit Economics’ Composite Purchasing Managers' Index for the eurozone registered 46.5 this month, unchanged from March. A reading below 50 indicates a contraction for the economy as a whole.

"The survey is signaling a worrying weakness in the economy … with signs that the downturn is more likely to intensify further in coming months," said Chris Williamson, chief economist at Markit.

Editor's Note: The ‘Unthinkable’ Could Happen — Wall Street Journal. Prepare for Meltdown