BOSTON (AP) — Fidelity Investments is ramping up its small presence in the rapidly growing exchange-traded fund business by expanding a 3-year-old partnership with BlackRock Inc.’s iShares unit, the largest ETF provider.

BlackRock, in turn, will be able to sell its iShares ETFs to a much broader range of investors. Fidelity has an industry-leading 18.5 million brokerage accounts.