The active fund industry has not fared any better, with between 71% and 93% of active U.S. stock funds, depending on the type, either underperforming their benchmarks or closing altogether over the decade ended June 30.

Meanwhile, ETF providers like BlackRock and Vanguard Group have gained a big following for their low-cost, passive strategies. Vanguard Group also recently became the second largest ETF provider as investors sought out the money manger’s cheap index-based options.

SEE MORE: Will DOL Rule Shakeup ETFs? ETF Trends, BNY Mellon Release Report

Looking ahead, the Department of Labor’s new so-called fiduciary rule is scheduled to go into effect in April. Financial advisors of retirement accounts will have to demonstrate that their decisions are in the best interest of clients, a change that observers expect will lead to more fee-based accounts instead of the current commission-based models. Consequently, more advisors may turn to cheap index funds to keep overall costs down.

“The case for passive is being made so well and so clearly,” Bullen added, “it has become common wisdom.”

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