Patience. That’s what investing in actively managed funds requires, according to a new study from Morningstar.

The study, by Paul Kaplan, director of research and Maciej Kowara, senior analyst, looked at the returns of several thousand actively managed equity funds over a 15-year period, from Jan. 1, 2003 through Dec. 31, 2017, focusing on their longest underperformance periods (LUP) and longest outperformance periods (LOP) versus their benchmarks.

It found that even funds that outperformed over those 15 years underperformed well over half that time, and vice versa.

The funds in the study were based around the world in the U.S., Canada, Europe and Asia, excluding Japan  and did not hedge their foreign currency exposure. The findings were based on only those funds that remained in existence for the full 15 years and, more specifically, on the performance of their oldest share classes.

Of the 5,500 funds studied, 3,790, or roughly two-thirds, beat their benchmark over the 15 years but on average underperformed their benchmarks nine to 11 years during that time.

“Investors who were hoping to hold outperforming funds over this 15-year period not only needed to pick the right funds but have the patience to endure periods of underperformance of nine to 11 years at some point within that period,” the study states.

Of the 1,710 that underperformed their indexes over the 15 years, 1,164 outperformed during 11 to 12 of those 15 years. “It would be a mistake to judge a fund’s ability to outperform its benchmark on a track record as long as 11 years,” the study notes.

It also advises against choosing funds based on “standard performance-measurement periods, such as three, five or even 10 years” which “are far too short to evaluate a manager with confidence.

“Investors who believe they picked a good fund must show more patience than is commonly assumed … a big dose of patience … an investing virtue that has not been emphasized enough,” the report says.

The study concludes by reminding investors investors that “active investing is a long game” where a “good manager” can underperform an index “for years.”

For investment consultants like advisors, it recommends against putting “too much stock in three- to five-year return records”  and for asset management firms, it suggests they consider “how they structure their bonuses for active managers.”

— Check out How Can Active Investors Survive in a Passive World? Get Small on ThinkAdvisor.