Assets held in U.S. exchange-traded funds rose 7.2% in March from the previous month to $806 billion, according to monthly data from State Street Global Advisors released last week. ETFs outpaced the Standard & Poor’s 500 Index, which rose 6%.

Ten of 12 ETF categories rose in March, according to State Street. The size and international categories accounted for 57% of the $54 billion gained overall in March.

As of March 31, there were 863 exchange-traded funds in the United States managed by 31 companies nationally.

The top three ETF managers collective accounted for 84% of the U.S. listed ETF assets, up 0.2 percentage points from a month earlier. BlackRock, which bought the iShares family of funds from Barclays, managed 47.8% of assets, State Street had 23.3% and Vanguard 12.9%.

Despite this powerful market share, other large companies are entering the ETF space. Last month, JPMorgan Chase & Co. announced in a pair of filings with the Securities and Exchange Commission that it plans to introduce a pair of exchange-traded funds.

The New York company said it plans to introduce both actively managed and index-based ETFs. It plans to launch its first actively-managed ETF later this year that would invest in about 300 domestic large-cap stocks. For such actively managed ETFs, JPMorgan wants to be able to have funds that can hold stocks, bonds, open-end funds, closed-end funds and unit investment trusts.

The company is also interested in a pair of index-based ETFs. They want one that tracks an index of investment-grade U.S. municipal bonds with maturities between one and 12 years, and another that will track investment-grade U.S. corporate debt with an issuance of at least $300 million.

Subscribe Now

Access to premium content including in-depth coverage of mutual funds, hedge funds, 401(K)s, 529 plans, and more.

3-Week Free Trial

Insight and analysis into the management, marketing, operations and technology of the asset management industry.