So far this earnings season, the less a U.S. company is exposed to America, the better its results. S&P 500 companies that generate more than half their revenue overseas are posting first-quarter earnings growth of 19.9 percent on average, double that of companies that conduct most of their business domestically, according to FactSet. About 60 percent of the S&P 500 has reported results. That helps explain the gap between the strong quarterly results and sluggish economic data like Friday's report showing U.S. GDP increased at just 0.7 percent in the first quarter, its slowest pace in three years. In fact, a CNBC analysis found that the difference between earnings per share growth and gross domestic product expansion in the first quarter is the widest since the third quarter of 2011. "We're seeing some pickup in growth that's outside the U.S. that's being reflected in these earnings numbers," said Nick Raich, CEO of The Earnings Scout, pointing out that "the U.S. data is domestic focused."

About 46 percent of S&P 500 sales overall come from foreign markets. The U.S. is still the world's largest economy, but its growth has stagnated while that of the rest of the world has been picking up. The International Monetary Fund last month raised its annual growth forecasts for China and the euro area by 0.1 percent from its report in January. The estimate for the U.S. economy was unchanged. The IMF raised estimates for Japan and the U.K. by 0.4 percent and 0.5 percent, respectively, for an estimated overall 0.1 percent uptick in global growth this year. This time last year, the IMF had cut its global growth outlook by 0.2 percent.