FEDFUNDS Meaning and Computation: The Effective Overnight Interbank Rate in the United States

The FEDFUNDS effective rate published daily by the New York Fed is not an FOMC decision: it is a market price, computed on the overnight uncollateralized interbank transactions executed the prior business day in the United States.

Three points anchor any rigorous reading: the computation methodology (revised in 2016), the exact nature of the underlying market (collapsed since 2008), and the strict distinction between effective, target, and futures.

1. The FEDFUNDS Effective Rate: Market Price Published by NY Fed at 9 a.m. ET

Each business day in the United States, at 9:00 a.m. Eastern Time, the Federal Reserve Bank of New York publishes the effective Federal Funds Rate on its Statistical Release H.15 page and on the FRED portal (Federal Reserve Economic Data) of the Federal Reserve Bank of Saint Louis. The published quantity is a market price, not a policy decision: it aggregates the overnight uncollateralized interbank transactions actually executed the previous day between institutions holding a reserve account at the Federal Reserve. Publication occurs at T+1 — Monday’s effective rate is known Tuesday at 9 a.m. ET.

The FRED series code is FEDFUNDS, and the series covers, without interruption, July 1954 through May 2026 — 72 years of daily data. No other major U.S. monetary series provides such uninterrupted historical depth. The Statistical Release H.15 also publishes the levels of other administered policy rates (IORB, ON RRP, discount window) and facilitates an integrated reading of the monetary corridor for market participants and researchers.

Published granularity is daily, with no intraday release. The Fed also publishes the OBFR (Overnight Bank Funding Rate), a very close quantity that aggregates somewhat more broadly (Fed Funds + Eurodollar). OBFR is primarily used to compare onshore and offshore bank liquidity but does not replace the effective Federal Funds Rate as the official reference for U.S. monetary policy (Federal Reserve Bank of New York, Reference Rates Methodology). The historical series is also accessible in the daily FRED FEDFUNDS series since 1954.

This article establishes the foundational definitions; for back to the central monetary policy signal and its inscription within the five-layer reading framework, see the cluster’s hub article.

2. The Computation Methodology: Volume-Weighted Average Since 2016

Since March 1, 2016, the effective Federal Funds Rate has been computed as a volume-weighted average of the prior day’s overnight uncollateralized interbank transactions. For each reported transaction, the NY Fed takes the loaned amount and the practiced rate; the weighted average sums the volume × rate products divided by the sum of volumes. The result is published at 0.01 percentage point precision (1 basis point).

This methodology replaced in March 2016 a prior simple arithmetic mean formula (Federal Reserve Bank of New York, 2016 methodology change). The change aimed to reduce sensitivity of the published rate to small-size transactions practiced at atypical levels — typically a few small banks exchanging modest amounts at 50 or 100 basis points below market, which artificially lowered the arithmetic mean without representing the genuine market condition. Under the new methodology, their weight in the calculation is proportional to volume actually transacted, eliminating this structural bias.

The gap between the two methodologies on the same day is generally small — a few tenths of a basis point — but can reach 5 to 10 basis points on dispersed transaction days or quarter-end. NY Fed published in its 2016 methodological release a retroactive analysis comparing the two series over 2014-2015, showing that the volume-weighted average delivers a more stable and more representative signal of effective interbank liquidity.

The computation perimeter includes Federal Funds purchases (reserve acquisitions) reported by major dealers to the Fed via the FR 2420 reporting form, and excludes collateralized repo transactions (aggregated separately in SOFR — Secured Overnight Financing Rate, also published daily by NY Fed since April 2018). The collateralized / uncollateralized distinction is fundamental: Fed Funds and SOFR measure two distinct markets that can diverge in stress periods — typical case being the September 2019 repo spike, where SOFR briefly jumped to 10% while effective Fed Funds exceeded IORB by only 20 basis points.

3. The U.S. Overnight Interbank Market: Volume Collapse Since 2008

The economic object measured by FEDFUNDS — the U.S. overnight uncollateralized interbank market — experienced a major structural break between 2008 and 2015. Before 2008, the Fed Funds market constituted the principal end-of-day adjustment valve: every bank holding a Fed reserve account had to close its position at a non-negative balance, and banks in deficit borrowed from those in surplus for a few hours at market-arbitrated conditions. Daily volumes typically reached 150 to 200 billion dollars during the 2000s.

Post-2008 QE flooded the system with bank reserves: from a few dozen billion in 2007, the total reserves stock rose to $3.2 trillion in May 2026 per Federal Reserve H.4.1 data. This structural overliquidity eliminated the systematic need for end-of-day interbank adjustment: nearly all banks now hold permanently and substantially excess reserves. Direct consequence, Fed Funds volumes effectively transacted dropped to $60-90 billion daily in 2025, less than half pre-crisis levels (Federal Reserve Bank of New York, Statistical Release H.15).

The market survives thanks to a very particular residual arbitrage segment. Federal Home Loan Banks (FHLBs) — financial institutions specialized in residential mortgage refinancing — hold significant liquidity but are not eligible for the Fed’s IORB remuneration (reserved for commercial banks and credit unions). They therefore lend this liquidity in the Fed Funds market, typically at 2 to 5 basis points below IORB. At the chain’s other end, U.S. subsidiaries of foreign banks borrow these funds and immediately redeposit them at IORB, capturing a spread of a few basis points on intraday operation without material credit risk (Wall Street Journal, September 2024; Liberty Street Economics, NY Fed).

This arbitrage flow represents the bulk of overnight Fed Funds transactions in 2025. Its economic logic has nothing in common with the market’s historical function: it is no longer interbank end-of-day position balancing, but a technical IORB-FHLB arbitrage mechanism exploiting the non-eligibility of certain counterparties for the upper administered rate. It is this residual mechanism that NY Fed aggregates daily, which explains two observed properties of the effective rate: very low intraday volatility (often less than 1 bp dispersion across same-day transactions) and near-permanent proximity to IORB minus a few basis points.

The operational consequence: the effective FEDFUNDS rate is no longer, since at least 2010, a genuine signal of interbank market tension in the sense it was in 1990 or 2000. Its modern reading proceeds through the effective-vs-target corridor mechanics and the dominant role of administered rates IORB and ON RRP, treated in a dedicated article of the cluster.

4. The Three Fed Funds Quantities: Effective, Target, and Futures

Any serious discussion of FEDFUNDS requires distinguishing three distinct quantities that share the same name but belong to radically different logics. Confusion between these three quantities is the most frequent analytical error on money markets.

The effective Federal Funds Rate, the subject of this article, is the market price published by NY Fed based on transactions actually executed the prior day. It is an ex post observation, computed under the volume-weighted methodology described in section 2. This quantity is not directly steered by the FOMC; it results from a market equilibrium constrained by the administered rates (IORB, ON RRP) that the FOMC sets in parallel.

The target range, the second quantity, is the policy decision announced at the conclusion of each Federal Open Market Committee meeting — eight regular meetings per year since 1986, plus possible extraordinary meetings in crisis periods (March 2020, September 2008). The FOMC has set the target as a 25-basis-point range since December 2008 (before that date, the target was a single point). In May 2026, the target range stands at 4.25-4.50% per the most recent FOMC communiqués. The target is not an observable quantity in the way the effective rate is; it is a policy declaration that applies until the next FOMC decision.

Fed Funds futures, the third quantity, are forward contracts traded on CME Group that express the market’s collective expectation of where the effective Federal Funds Rate will sit in coming months. Each contract references the monthly average of the effective rate for the reference month and settles in cash at expiration. The Fed Funds futures curve at various horizons provides a continuous reading of market expectations on future FOMC decisions — it is the primary input of the CME FedWatch tool, which computes implied probabilities for each upcoming FOMC meeting. Volumes traded on Fed Funds futures are massive: several hundred thousand contracts daily depending on the session, representing notional value of several hundred billion dollars (CME Group, Daily Volume Reports).

Confusing these three quantities systematically produces erroneous analyses. Citing “the Fed Funds at 4.33%” is ambiguous without qualification: prior-day effective rate? Upper bound of the target range? 6-month-out futures-implied anticipation? Each of the three values informs a different question — current state of the money market, Fed’s policy stance, or collective expectation on its forward path. For an integrated reading of the three quantities and their articulation within the Fed reaction function, see the central-bank instrument set within the parent sub-pillar.

Last updated — 19 May 2026