Hedge fund manager and author Joel Greenblatt says that the majority of top mutual fund managers spent at least three years lagging well behind others, says a CNBC article by Validea CEO John Reese.

This, however, is something short-term investors tend to run from, Reese writes. An unfortunate move, since over the long-term these same managers tend to outperform. He argues, “Reaching for returns that beat the benchmark requires the emotional discipline to stick with an investment manager through thick and thin, knowing that no strategy can beat the market all the time.”

Reese uses the example of Warren Buffett, billionaire head of Berkshire Hathaway who, according to analysis by Boston-based firm Newfound Research, “underperforms the broad index about once every three years,” and has had “10 periods when he missed the benchmark by 10 percent or more over a significant period of time.” However, between March 1980 and October 2016, Newfound’s findings showed that Berkshire shares returned 20.2 percent, nearly 10 percent more annually than the S&P 500.  Reese adds that Berkshire is up 25 percent this year (15 percent since November). Buffett, he writes, “famously says investors should take advantage of downturns to buy what others are selling.”

Which calls for a bit of intestinal fortitude. Reese concludes, “An investor who understands there is a certain element of risk to investing is more likely not to panic when the market goes awry.”