Regardless of whether you’re buying shares of companies based in Kuala Lumpur, Malaysia or Kalamazoo, Michigan, they’re generally driven by the same fundamentals. Is the business growing? Are earnings consistently rising? Does the company carry a lot of debt? If the answers are yes, yes and no, odds are the shares should be rising. International investing does add one additional layer of complexity, though –currency.

The U.S. dollar has been on a tear since the Great Recession, with the Dow Jones FXCM Dollar Index up by more than 25% since 2011 alone. The index measures the performance of the U.S. dollar against the euro, the British pound and the Japanese yen, which together account for around 80% of worldwide currency spot market trading.

The strengthening dollar is good news for American consumers, because it makes imported goods and services cheaper. That has actually helped keep a lid on inflation here in the U.S. in the post-recession years, with the dollar reversing nearly a decade of declines in 2008 as more foreign investors bought dollars and treasuries as a safe haven.

The strengthening dollar is bad news for American investors who own shares of foreign companies, though, since earnings in yen, euros and ringgits become less valuable in dollar terms. That, in turn, drags down share prices.

The graph below shows the performance of the Dow Jones FXCM Dollar Index and the Vanguard FTSE Emerging Markets ETF. While there isn’t a perfect one-for-one correlation between the two indexes, you can see that when one is rising, the other is usually falling.

Right now, the dollar is taking a bit of a breather after its long rally. It had gained nearly 12% in the back half of 2014 – its biggest gain in years – as more and more market watchers began betting that the U.S. Federal Reserve would raise interest rates in 2015. With most of the world still in easing mode, a bump up in rates here would make dollar denominated assets much more attractive. And as we saw when the Fed dropped our own rates effectively to 0% and U.S. investors began flooding into foreign markets, investors always seek out the best yields.

But while the Fed continues to signal that it will act on rates sometime this year and forecasts that the benchmark interest rate will end the year at 0.625%, so far it has been slow to move. With U.S. inflation still quite low and quite a bit of slack in the labor market, some are beginning to wonder if there will an increase this year unless inflation picks up radically in the back half. As a result, interest in the dollar is beginning to wane and the dollar index has slid by about 2% so far in June alone.

So while the mixed economic picture isn’t exactly good news, it does mean the dollar could slide further from here. That’s especially true if the Europeans are finally able to put concerns about a Grexit to bed, which isn’t entirely unlikely. That could certainly spark a rally in the euro. This isn’t the first time the Greeks have played hardball, only to cave or win concessions in the eleventh hour. If the Greeks do ultimately leave (or get forced out of) the euro zone, look for the dollar to make a run higher, in which case foreign stocks and bonds will likely remain under pressure.

Regardless though, the global economic situation will certainly return to some semblance of normal and it will happen sooner rather than later. When it does, the dollar won’t be as attractive as a safe investment, in which case foreign stocks and bonds – particularly those of the other Pacific Rim nations – will certainly become attractive again.