The April move will mark the end of a two-year stint at the company for Bodnar, who was previously global head of BlackRock Sustainable Investing. He took up his most recent role during a reorganisation of BlackRock's sustainability efforts in October.

It follows a tough time for the company as it faces pressure from campaigners to push for faster climate action by companies, and concern from some U.S. politicians that doing so could impact investor returns.

The memo said BlackRock assets invested through its dedicated sustainable investing platform now stood at around $500 billion of its total of roughly $8.6 trillion in assets, and Bodnar had been "central to that success".

"Paul approached us recently with a plan to return to his career path in the impact world, and today it will be announced that he will be joining the Bezos Earth Fund to oversee programs that involve collaboration among financial services, the real economy and governments," the memo said.

(Reporting by Simon Jessop; Editing by Mark Potter)

By Simon Jessop