Fidelity Investments announced today it will offer free trading on 25 widely held iShares exchange-traded funds, including some of the most popular ETFs in the world, including the iShares S&P 500 ETF (NYSEArca: IVV), iShares MSCI EAFE ETF (NYSEArca: EFA) and iShares MSCI Emerging Markets ETF (NYSEArca: EEM).

The brokerage giant said it has partnered with iShares’ sponsor BlackRock to offer free trades “for a period anticipated to be at least three years.”

The move comes just months after Fidelity’s arch competitor, Charles Schwab, launched its own family of ETFs and offered Schwab brokerage customers the opportunity to trade those funds for free. Schwab currently offers six such ETFs, and is planning to launch at least two more.

The Fidelity/BlackRock deal covers a much broader spectrum of ETFs, including ETFs covering most major equity and fixed-income categories. It covers 10 of the 25 largest ETFs in the U.S.

The move could help drive significant retail interest in ETFs. Commissions make retail strategies like dollar-cost-averaging unviable. By removing that barrier, brokerages like Schwab and Fidelity could help ETFs grab a larger share of the mutual fund marketplace.