JP Morgan struck a deal to be the custodian for more than $1 trillion of BlackRock’s assets, poaching the business from State Street, a person familiar with the matter said.

JP Morgan will spend around two years bringing the assets into its existing $20.5 trillion platform, this person said. That may elevate the New York bank to the No. 2 player in the business, second to Bank of New York Mellon, which has about $28 trillion assets under custody, according to recent company filings.