The S&P 500 and Dow hit new highs. You see the headlines everywhere. Another record. Wall Street doing what Wall Street does. But Reuters makes a point this week that most American investors probably haven't stopped to consider. From a global perspective, the performance of Wall Street is far from exceptional.

I know that sounds wrong. It felt wrong to me the first time I read it.

The Reuters piece doesn't lead with comparative return tables. It makes the case that when you look beyond U.S. borders, American stocks aren't the runaway leader everyone assumes they are this year. I can't give you a clean percentage comparison because I haven't verified the specific numbers myself, and I'm not going to pretend I have. The argument deserves to be taken seriously, though, especially by anyone whose portfolio is almost entirely domestic.

One mechanism worth understanding is how currency affects these comparisons. When the dollar weakens against other currencies, overseas returns look better once you translate them back into greenbacks. A foreign stock's gain in its home currency gets a boost when the dollar declines relative to that currency, so the same performance looks bigger to a U.S. investor. That math works in the background, silently, and most people never think about it.

The other part of the story is valuation. I have seen the general pattern described in enough places over the years, that international markets, particularly in Europe and parts of the emerging world, have traded at lower valuations than U.S. equities for a while. I am not going to cite a specific price-to-earnings ratio or CAPE figure here because I have not pulled the current numbers myself. But the directional argument is sound. When you start from a lower price, you have more room to climb.

I have been investing for forty years and I have watched this pattern repeat itself more times than I can count. U.S. stocks dominate for a while, everyone declares international diversification dead, and then the rotation happens. Money flows where valuations are reasonable. The cycle turns. People who held a boring mix of domestic and international funds suddenly look smart again.

Here is a question worth asking yourself. When you check your portfolio, do you actually know what percentage sits in non-U.S. stocks? In my experience, the investors I talk to are running portfolios that are heavily weighted toward American companies, sometimes to the tune of 80 or 90 percent. Sometimes by choice. Often by default, because the target date fund in their 401(k) skews toward U.S. equities, or because they only ever bought VTI and called it a day.

There is nothing wrong with VTI. I have recommended it as a first investment and I stand by that. But a total U.S. market fund is still a total U.S. market fund. It gives you no exposure to the more than a third of global market capitalization that lives outside our borders.

My friendly sparring partner Cassie Welch would probably tell you that international exposure adds risk, and she would not be entirely wrong. Currency fluctuations cut both ways. Political instability in emerging markets is real. Governance standards vary. These are legitimate concerns.

But concentration risk is also real. Betting everything on a single country, even one as economically dominant as the United States, is a bet. You are just so used to making it that it does not feel like one.

I am not telling you to sell your S&P 500 index fund and move everything overseas. If your portfolio has not seen an honest review in a while, this might be a fine time to look at your actual allocation. The global market may be telling you something this year. Whether you listen is up to you.

As always, I am sharing perspective here, not professional financial advice. Talk to an advisor before making changes that affect your retirement.