While the S&P 500 has performed well this year, with the index of U.S. large-cap stocks rising nearly 12 percent to hit a series of record highs, international equities have performed even better.
The popular iShares ETF tied to the MSCI EAFE index and known by its EFA ticker has surged almost 19 percent in 2017. The ETF tracks large stocks from developed markets outside the U.S. and Canada.
Its impressive performance comes after three-straight negative years. In fact, if the year closes with the EFA outpacing the S&P 500 ETF (SPY) by the current 6.8 points, the internationally focused ETF would have logged its most dramatic outperformance since 2006.
The 2017 run represents "a reversion to the mean," said Boris Schlossberg of BK Asset Management, referring to the supposed tendency of one year's underperformers to outperform, and vice versa.
"Whether this reversion to the mean continues? That answer, I think, is yes," Schlossberg added Tuesday on CNBC's "Power Lunch." "They are early on in the recovery cycle."
"I think the bet here is to go long ETA and short S&P, if you want to do a long-short trade," Schlossberg said.
While Craig Johnson, unlike Schlossberg, is bullish on U.S. stocks, the chief market technician at Piper Jaffray agrees that "I want to stay long the international socks, because I think that the outperformance is going to continue for a while longer."
This assessment is "just based on the charts," which show increasing momentum for the EFA, he said.
Within the ETF, the biggest country component is Japan, with a nearly 23 percent weighting, followed by the United Kingdom at 18 percent, France at 11 percent and Germany at 10 percent.