Kudlow's Strong Dollar Is Easier Said Than Done

A rising or falling dollar in any given year doesn't appear to have much of an impact on U.S. stocks. Since 1974, the S&P 500 had an average annual return of 11.6% in years when the dollar rose. And when the dollar fell the S&P was up 10.4% per year, a small difference. But foreign stocks have seen a huge divergence between up and down annual periods in the dollar. When the dollar rose, the MSCI EAFE was up just 4.7% annually while down years in the dollar saw foreign stocks gain 16.7% a year.

It's estimated that almost 45% of sales for large-cap corporations come from overseas as many U.S. companies are multinational. So it's possible that the relationship between U.S. stock market performance and the dollar may not be as clear cut in the future but currency fluctuations will certainly continue to play a role when investors hold assets outside of their home country.

Kudlow also stated that he would like to see the dollar, "a wee bit stronger than it is currently, but stability is the key." This one could be difficult to pull off. Here is a chart of the dollar index going back to the early-1970s:

While the dollar has basically gone nowhere from start to finish over this 45-year-plus period, it has been highly volatile. In fact, the volatility of the dollar index is more than 7%, which is roughly half that of the stock market. For a data series that doesn't go up and to the right over time like the stock market, currencies can see wild fluctuations.

The historical investment relationships in a strong dollar regime are pretty clear — gold and foreign stocks tend to underperform. The problem is that it's not always easy to predict the direction or magnitude of the move in the dollar. Currencies are affected by a large number of variables and don't always do what politicians or economists would like them to.

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Ben Carlson is director of institutional asset management at Ritholtz Wealth Management. He is the author of "Organizational Alpha: How to Add Value in Institutional Asset Management."