MarketWatch Premium: Adding international stocks to your portfolio can help you endure any pain in the U.S. market

Someday you will be glad your stock portfolio includes international equities.

That day is not yet here.

The first three months of this year were yet another in a long string of quarters in which international diversification didn’t pay off for a U.S.-based investor. In contrast to the 5.4% loss of the total U.S. stock market, global stocks…