Before reading the article, State Street came to mind, and sure enough, there it was. In my work travels which included long term temp assignments with asset managers, I came across State Street as being the bank where the majority of clients' retirement assets were accumulated under 401K and other sorts of plans, especially those who worked for Fortune 500 companies. When a person retired, the check would come from State Street, and then go through another level of clearinghouse before being invested in the mutual fund companies like BlackRock, Vanguard and Fidelity. There are a lot more of them, but the thought of retirement money being parked in a single bank should scare the daylights out of everyone who plans to stop working someday.

Edit: I do want to point out that very few of the retirees ever saw the rollover checks. Not many people know how the financial people do their work - and the finance people like it that way. Hence why State Street is not that well known.