The buoyant American stock market may be blinding investors to better opportunities abroad.

Sure, the decade-old bull market at home has been a boon to investors, driven by technology giants like Amazon, Apple and Microsoft. The S&P 500 has beaten the MSCI All Country World Index in total annualized returns, by 13.5 percent to 8.8 percent, since 2010 to the end of 2019.

But that’s not to say overseas markets have been doing poorly.

In several years over the last decade, stock markets in other developed economies, including Denmark, New Zealand and Austria, have turned in better performances.

Investors whose portfolios are heavily weighted to giant American companies may think they’re getting overseas exposure because those companies earn revenue abroad, but that’s not quite the same thing as investing internationally. The United States stock market makes up about half of the world’s market value, so there are plenty of opportunities to shop elsewhere.

Those who would like to add some international flavor to their portfolios need to be aware of a downside. Overseas markets may underperform American stocks, hurting portfolios.