A repurchase agreement (repo) is a financial transaction in which one party agrees to sell securities to another party and repurchase them at a later date. This agreement is also known as a collateralized loan, as the securities being sold are used as collateral for the loan.

In a repo, the buyer of the securities – also known as the lender – loans money to the seller of the securities – also known as the borrower. The borrower agrees to repurchase the securities at a specified price and date. The difference between the selling price and the repurchase price is the interest earned by the lender.

The securities being sold in a repo are typically government securities, such as treasuries, or securities issued by government-sponsored enterprises, such as Fannie Mae and Freddie Mac. These securities are considered safe investments, as they are backed by the full faith and credit of the U.S. government.

Repurchase agreements are commonly used by banks, money market funds, and other financial institutions to manage their liquidity. These institutions can use repos to obtain short-term cash by pledging their securities as collateral. This allows them to meet their funding needs without having to sell their securities outright.

Repurchase agreements also play an important role in the Federal Reserve`s efforts to manage the money supply. The Fed can use repos to inject liquidity into the financial system by buying securities from banks and other institutions. Conversely, the Fed can use repos to drain liquidity from the system by selling securities to these same institutions.

In conclusion, a repurchase agreement calls for an investor to buy securities for a specified price and then sell them back at a higher price at a later date. This type of agreement is widely used in the financial industry for managing liquidity and is an important tool for the Federal Reserve in its efforts to manage the money supply.