In a recent article for The Wall Street Journal, columnist Jason Zweig discusses the pros and cons of a newly proposed fund called the “Forever Fund” in which investors would lock up money for at least 10 years.

The fund idea—still only a “thought experiment”–was created by Cambria Investment Management executive Meb Faber who, writes Zweig, wants investors to take a longer-term view “in a world of itchy-fingered traders.”

“While I’m a fan of the idea,” Zweig writes, “psychology and history suggest it is easier to imagine than to implement.” He adds, “other versions of the idea have ultimately flopped.” But he adds that Faber would entice investors to bite with low management fees that decrease over time and would discourage early redemptions with penalty fees that would be “put back into the fund as a bonus to the loyal investors.”

Zweig cites two examples of similar funds that performed well early on but made investors nervous as the years progressed. He also cites data from World Bank that shows “investors in the U.S. seem nowadays to be among the twitchiest on earth.” According to the data, the total value of shares traded relative to average market cap (called the portfolio turnover ratio) was 133% in 2017, which equates to a holding period of only nine months—compared to an average holding period of five years in the 1970s. But averages can be misleading, Zweig explains, since a minority of extremely active traders can bring down the average and make it seem as if “everyone is more active than the typical person is.”

Zweig concludes that anything to increase investor patience is a good thing and suggests that maybe offering investors an out is the best enticement. He writes, “The key to getting people to lock up their money for the long run is giving them the feeling they are free to crack the safe anytime they want.”