A repo is a securities-collateralized short-term loan at the core of U.S. money markets. The Federal Reserve Bank of New York uses repo and reverse repo operations to keep the fed funds rate within target, SOFR benchmarks the overnight cost, and the Office of Financial Research puts average daily exposures at $12.6 trillion in Q3 2025.
What Is a Repo? Definition, Economic Substance, and Its Central Role in Markets
A repurchase agreement (repo) is a secured money market transaction in which one party buys securities from a counterparty while agreeing to resell them at a later dateCITE:E3. The Federal Reserve Bank of New York states that a repo transaction is economically similar to a loan collateralized by securities and temporarily increases the supply of reserve balances in the banking systemCITE:E3. The same institution notes that the Secured Overnight Financing Rate (SOFR) — a broad measure of the cost of borrowing cash overnight collateralized by Treasury securities — is built directly on this activity, underscoring how central repo is to overnight funding marketsCITE:E1.
SOFR: How Is the Cost of Overnight Repo Financing Measured?
SOFR is a broad measure of the cost of borrowing cash overnight collateralized by Treasury securities, published by the Federal Reserve Bank of New YorkCITE:E1. The rate is calculated as a volume-weighted median of transaction-level tri-party repo data collected from the Bank of New York Mellon and the U.S. Department of the Treasury's Office of Financial Research (OFR)CITE:E2.
Reverse Repo: The Symmetric Financing Mechanism
A reverse repo is the mirror image of a repo: the Desk sells securities to a counterparty under an agreement to repurchase them at a later dateCITE:E4. The Federal Reserve Bank of New York describes a reverse repo as economically similar to borrowing collateralized by securities, an operation that temporarily reduces the supply of reserve balances in the banking systemCITE:E4.
What Role Does Repo Play in Monetary Policy Implementation?
Repo and reverse repo operations support monetary policy implementation by helping keep the federal funds rate within the FOMC's target rangeCITE:E5. The Federal Reserve Bank of New York states that these open market operations also smooth market functioningCITE:E5.
Who Participates in the Repo Market and How Is It Used?
Repos provide short-term financing to banks, securities dealers, and other financial institutionsCITE:E6. In an August 24, 2022 analysis, the Office of Financial Research states that these institutions use repo funding to support their liquidity provisions and leveraged investmentsCITE:E6.
How Large and Systemically Important Is the U.S. Repo Market?
The U.S. repo market averaged about $12.6 trillion in daily exposures in the third quarter of 2025CITE:E7. The Office of Financial Research published this sizing estimate on December 4, 2025CITE:E7.
What This Means
Taken together, these facts describe one funding mechanism operating at two linked scales. The Federal Reserve Bank of New York relies on repo and reverse repo operations to keep the federal funds rate within the FOMC's target rangeCITE:E5, while SOFR — calculated from the same tri-party repo data collected by the Bank of New York Mellon and the OFRCITE:E2 — gives that mechanism a daily, published priceCITE:E1. The market that banks, dealers, and other financial institutions use to fund liquidity provision and leveraged investmentsCITE:E6 is the same market the OFR sized at $12.6 trillion in average daily exposures for Q3 2025CITE:E7, and the same market the Fed leans on to execute policy through repo and reverse repo agreementsCITE:E3CITE:E4.
Author's Take・EffectStory 編輯部
The scale is the headline: an average $12.6 trillion in daily exposures in Q3 2025, per the Office of Financial Research, makes repo the plumbing beneath both bank balance sheets and Fed policy execution, not a niche funding tool. What stands out is the shared data pipeline — SOFR is built from the same tri-party repo transaction data collected by the Bank of New York Mellon and the OFR that also feeds the Fed's own reverse repo operations to hold the fed funds rate inside its target range. That overlap means a single market, used by banks, dealers, and other financial institutions to fund liquidity provision and leveraged positions, carries both private funding risk and public policy transmission in the same pipes. The indicator worth watching next is any updated OFR reading on daily repo exposures beyond the $12.6 trillion Q3 2025 baseline, since it is currently the only quantified gauge of how that dual role is scaling.