A long-standing tenet of investingย holds that, to earn a higher investmentย return, one must be willing toย embrace a higher degree of risk. And,ย historically, small-cap stocks haveย had greater returns compared toย their large-cap counterparts, but haveย carried a higher level of volatility.

International stocks, meanwhile, haveย typically been more volatile than U.S.ย stocks, presenting investors with anotherย equity category to navigate.ย That long-standing tenet of investingย was challenged by groundbreaking workย released in 1952 by Harry Markowitz,ย who introduced the concept of modernย portfolio theory (MPT).

MPT, which won Markowitz theย Nobel Prize in economics, holds thatย while individual assets may be highlyย volatile, multiple assets blended togetherย make it possible to construct aย portfolio with relatively high returnsย and reduced volatility.

This can be achieved by blending assetsย that are not markedly correlated. If two assetsย have a perfect correlation, meaning thatย they produce the same return with the sameย level of volatility, they have a correlation ofย one. Conversely, if two assets have a correlationย of zero, they have no connection whatsoever.ย Assets with a low correlation areย likely to perform in a different manner overย time with varied reactions to market newsย and economic indicators.

An increased investment couldย act as a much-needed diversifier to your portfolio.

Portfolios as a whole will naturally strayย from their initial allocation, as the better performingย asset classes grow into a largerย percentage of the total. Since their lows inย 2009, U.S. markets have significantly outperformedย international markets, by a factorย greater than two to one.

A diversified portfolio from 2009 whichย had not been rebalanced by the end ofย 2016 would have become heavily weightedย toward U.S. stocks, versus its initial allocation.ย The portfolioโ€™s owner would haveย welcomed that development, as the Standardย & Poorโ€™s 500 index returned 11.96ย percent in 2016, while the MCSI Europe,ย Australasia and Far East (EAFE) index returnedย a mere 1.00 percent.

Of course, there have been many periodsย when international equity returns exceededย those of domestic equities. However, it isย unusual to have an eight-year run of U.S.ย equity dominance. This can be attributed toย the United States rebounding from theย Great Recession faster than expected, andย the dollar having been stronger than mostย international currencies.

By most financial metrics, domesticย stocks have reached loftier valuations relativeย to their international peers. The domestic equity markets are trading at aย price-earnings multiple of 18, while the internationalย markets are trading at a multiple of 12. This differential has begun to be reflectedย in performance, as the return on the S&Pย 500 was 11.93 percent through August 31,ย 2017, versus an EAFE return of 17.05 percent.

The MSCI Emerging Markets index, representingย the smallest economies in the world, isย now actually leading the pack, at 28.29 percent.

So, how can you take advantage of theseย developments? For one thing, you can investย in a variety of ways internationally. There areย countless exchange-traded funds, activelyย managed mutual funds and index mutualย funds in that category.

At Sterling, we prefer not to buy broadย international index funds, as they own interestsย in the entire market. This includesย certain industries, such as European banks,ย that we would rather not incorporate intoย our portfolios. Instead, we seek activelyย managed international equity mutual funds,ย put through rigorous vetting, to complementย our individual stock selections.

Overall, quality portfolio oversight requiresย a periodic review of asset allocation,ย and a subsequent rebalancing. This fall mayย be an opportune time, for instance, to evaluateย your own international exposure. Foreignย equities have become underweighted overย the last decade, so an increased investmentย could act as a much-needed diversifier toย your portfolio.