(Bloomberg) -- Heidi Richardson, who leads investment strategy for BlackRock's ETFs in the U.S., is leaving the firm.

Richardson, who has worked at BlackRock since 2010, will depart in May, confirmed Peter McKillop, a spokesman for the firm. He said her position hasn't been filled yet.

The world's largest provider of ETFs is trying to protect its dominant position as rivals led by Vanguard make steep fee cuts on passive products. BlackRock took in a record $64.5 billion into its iShares ETFs in the first quarter, and $140 billion last year, helped by price reductions on stock and bond funds aimed at buy-and-hold investors.

Richardson is part of a group that provides macroeconomic and market insight and offers clients investment ideas for using iShares ETFs, according to the firm's website. She didn't return a call for comment.

The iShares unit has had other departures in recent years. Nicole Hunter, who worked for the capital markets team, left in March.

BlackRock, the world's largest asset manager, has $1.4 trillion in ETFs.

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