US custodian bank State Street Corporation is buying the overseas custody business of Japanese banking and financial conglomerate Mizuho Financial Group for an undisclosed sum.

Mizuho Group had more than US$600 billion of overseas assets as of end-2024, comprising $580 billion under custody and $24 billion under administration, and overseen by its units in Luxembourg and the US.

State Street announced the acquisition. It will begin offering global custody services to Mizuho’s Japanese clients when the deal is completed, expected by the fourth quarter. Meanwhile, Mizuho will continue to provide clients with custody services for domestic assets.

According to Hiroshi Kobayashi, State Street’s head of Japan, the added scale from the acquisition will further expand its technology and service capabilities, and enhance service experience for Japanese clients.

“Having deep familiarity with the requirements and expectations of Japanese institutional investors, we look forward to meeting their needs not only in global custody but also data management, risk and performance analytics, currency management and securities finance,” he says.

Boston-based State Street had $46.6 trillion of assets under custody and/or administration as of end-2024.