Most repos involve banks, investment banks, money dealers and various investors.
>What Is a Repurchase Agreement?
>A repurchase agreement (repo) is a form of short-term borrowing for dealers in government securities. In the case of a repo, a dealer sells government securities to investors, usually on an overnight basis, and buys them back the following day at a slightly higher price. That small difference in price is the implicit overnight interest rate. Repos are typically used to raise short-term capital. They are also a common tool of central bank open market operations.
>What Is a Repurchase Agreement?
>A repurchase agreement (repo) is a form of short-term borrowing for dealers in government securities. In the case of a repo, a dealer sells government securities to investors, usually on an overnight basis, and buys them back the following day at a slightly higher price. That small difference in price is the implicit overnight interest rate. Repos are typically used to raise short-term capital. They are also a common tool of central bank open market operations.
https://www.investopedia.com/terms/r/repurchaseagreement.asp