Additionally, as foreign countries contribute to a larger portion of the global economy, investors should consider the growing force overseas. The U.S. represented about a third of global output 30 years ago, but now the U.S. makes up about 20%.

“There is a more basic reason to bring down the significant US overweight evident in many portfolios: diversification still matters,” Koesterich added. “Over the long term, a more geographically diversified portfolio should lead to better risk-adjusted returns.”

The strategist pointed out that over the past three years, inter-country correlation has dipped to 0.53 or to pre-crisis averages. Consequently, investors may benefit more from international diversification now than the post-crisis environment.

For more information on investing around the globe, visit our global ETFs category.

Max Chen contributed to this article.