Yields & Spreads

SOFR — Secured Overnight Financing Rate

SOFR is the cost of borrowing dollars overnight against US Treasury collateral — the post-LIBOR benchmark for nearly every dollar-denominated floating-rate contract. It tracks the Federal Reserve's policy rate almost exactly during calm times and tells you, immediately, when something has gone wrong in the repo plumbing of the US financial system.

May 14, 2026SOFRmoney-markets · repo · fed-policy · libor-transition

SOFR

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The plumbing rate. SOFR is the cost of overnight money in the secured part of the dollar funding market — and unlike most economic indicators, the rate isn't a forecast or an expectation, it's literally the price at which roughly $2 trillion of actual transactions cleared yesterday. When SOFR is well-behaved, it tells you the funding markets are operating normally and the Fed's policy stance is being transmitted to the rest of the financial system. When SOFR spikes — even briefly — it tells you something is broken in the plumbing, often before that something becomes a headline crisis.

SOFR

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What it measures

SOFR is calculated daily by the New York Fed as the volume-weighted median rate from three segments of the Treasury-collateralized repo market:

Together these three sources cover roughly $2 trillion of daily transaction volume — by far the largest underlying volume of any major rate benchmark globally. The rate is published the morning after the reference business day on the NY Fed website and is republished by FRED as series SOFR. The transaction-based methodology — as opposed to LIBOR's submission-based approach — is what makes SOFR resilient to manipulation and statistically grounded.

There are also longer-dated versions: 30-day SOFR, 90-day SOFR, and 180-day SOFR (called Term SOFR, published by CME), which are used in floating-rate contracts that reset on monthly or quarterly schedules.

Why it matters

Two angles.

The contract-benchmark angle. SOFR is the rate that almost every new US dollar floating-rate contract references. That includes: corporate bank loans (the syndicated leveraged loan market is now primarily SOFR-indexed), floating-rate corporate bonds, adjustable-rate mortgages (most ARMs reset to SOFR plus a margin), interest-rate swaps and futures (the CME's SOFR futures complex is the largest interest-rate-derivative market in the world), and student loans and other consumer floating-rate products. When the Fed changes rates, SOFR moves first; then everything indexed to SOFR resets at its next reset date. The total notional of contracts indexed to SOFR is in the hundreds of trillions — every basis point matters for someone.

The financial-plumbing-monitor angle. The overnight repo market is the circulatory system of the financial system. Trillions of dollars in collateral and cash exchange hands every day through it; dealers, money market funds, hedge funds, and pension funds all rely on it for short-term funding and investment. When that market malfunctions — collateral becomes scarce, balance sheet capacity tightens, year-end pressures bite — SOFR spikes. Those spikes are the earliest warning signs of stress. Watching SOFR is how you tell the difference between "the Fed has set policy and the market is calmly accommodating" versus "something is wrong and the Fed may have to intervene before next week's headlines."

What moves it, and what it moves

Moves SOFR:

The federal funds rate target. Direct mechanical link — SOFR trades within the Fed funds target range almost always.
Reserve balances in the banking system. When reserves are abundant (post-QE), SOFR runs near the bottom of the Fed funds range. When reserves drain (QT, large Treasury auctions, tax payments), SOFR drifts upward in the range and can briefly spike.
Collateral supply. Treasury issuance shifts the supply of repo collateral. Large auction settlements (especially of 30-year bonds) drain cash temporarily, pushing SOFR up by a few basis points for several days.
Year-end / quarter-end balance sheet pressure. Banks shrink balance sheets at reporting dates to meet regulatory capital ratios. This reduces their willingness to provide repo financing, pushing SOFR up. The December 31 print is reliably elevated.
Tax payment dates. April 15 (individual tax due date) and quarterly corporate estimated tax dates pull cash out of the system, briefly tightening repo and pushing SOFR up.

SOFR moves:

Floating-rate loan reset levels (most syndicated loans, ARM mortgages, and floating corporate bonds reset on 1-month or 3-month SOFR).
The CME SOFR futures and options complex (the largest interest-rate-derivative market in the world).
Bilateral interest-rate swap pricing (any swap that's collateralized at a central counterparty references SOFR by default now).
Money market fund yields (which converge to SOFR within a few days of any Fed move).
Margin requirements at clearinghouses (which scale with SOFR-derived funding costs).

A worked example: the September 2019 repo spike

For most of 2019, SOFR traded near the bottom of the federal funds target range — typically 2.10-2.15% against a target range of 2.00-2.25%. The repo market was orderly, dealer balance sheets were comfortable, and reserves in the banking system were elevated from years of QE.

Then September 17, 2019. A combination of factors compressed onto a single day:

A large corporate tax payment was due (~$30 billion drained from money market funds to the Treasury)
A large Treasury auction settled ($54 billion of new debt added to dealer balance sheets, needing financing)
Bank reserves had been gradually drained by QT through 2018-2019, falling well below the level the system needed for friction-free repo

By 9:00 AM, SOFR was trading at 5.25% — more than 300 basis points above the upper bound of the Fed funds target range. The repo market was, in technical terms, broken: dealers literally could not find anyone willing to lend cash against Treasury collateral at a reasonable rate.

The Fed intervened within hours. The New York Fed opened a Repo Facility (its first such operation since the 2008 crisis), offering dollars in exchange for Treasury collateral at rates near the federal funds target. By the end of that week, the Fed had injected over $200 billion of liquidity. SOFR returned to its normal range within a few days. But the episode produced a permanent change in Fed operating procedure: the SRF was created in 2021 specifically to put a permanent ceiling on SOFR and prevent a repeat.

The September 2019 spike is canonical because it illustrated, in real time, that the Fed's target rate is a guideline — the actual market rate, SOFR, can wander dramatically when the plumbing is stressed. Subsequent monitoring of SOFR has become an essential part of how the Fed calibrates its balance sheet decisions.

The current cycle, and the open question

SOFR's mean-level behavior is now well-understood — it tracks the Fed funds target range with high fidelity. The interesting questions are about its tails:

How abundant are reserves now? The Fed has been running QT, draining reserves. The level at which "abundant" tips into "scarce" — and SOFR starts wandering above the target range — is the operationally interesting threshold. Most estimates put that level somewhere around $3 trillion of total reserves (currently we're at roughly $3.3-3.4 trillion, depending on which measurement).
Will the SRF be needed? The SRF has been used in small quantities at quarter-ends since 2021, but never in a major stress event. Whether it actually backstops SOFR in a real liquidity crisis — or whether dealers can't or won't use it for stigma reasons — is unknown.
Quarter-end and year-end spikes. These have become consistently elevated since 2022. The December 31 SOFR print is now reliably 10-30 bps above the daily average for the week. This is non-zero stress that's been normalized into routine market behavior.

Watch points: the spread between SOFR and the Fed's Reverse Repo Facility (RRP) rate (when this widens, signals reserve scarcity); the daily SOFR percentiles published by NY Fed (when the 99th percentile spikes, plumbing stress is showing in the tails); the size of SRF usage (any large drawdown is significant); and the spread between SOFR and EFFR (Effective Federal Funds Rate) for a clean read on secured-vs-unsecured market stress.

FAQ

What is SOFR, in one sentence?

SOFR is the volume-weighted median rate at which dealers borrow dollars overnight against US Treasury collateral, calculated daily by the New York Fed from roughly $2 trillion of actual transactions in the repo market. It replaced LIBOR as the benchmark rate for new US dollar floating-rate contracts in 2022.

Why did SOFR replace LIBOR?

LIBOR (London Interbank Offered Rate) was a survey rate — banks were polled daily about what they thought the cost of unsecured interbank borrowing would be, and an average was published. The 2008 financial crisis exposed two flaws: (1) the unsecured interbank lending market that LIBOR was supposed to measure had effectively stopped existing, so banks were making up answers; (2) the survey was easy to manipulate — proven by the 2012 LIBOR scandal in which traders coordinated submissions to benefit their derivatives positions. Regulators mandated a transition to a transaction-based, secured benchmark. SOFR, derived from real Treasury-repo transactions, satisfied both criteria. The LIBOR cessation deadline was June 30, 2023; almost all US dollar contracts have migrated.

Why does SOFR sometimes spike sharply, like in September 2019?

Because the overnight repo market is a real, finite market with finite balance sheet capacity and finite supply of collateral. On any given day, dealers' aggregate cash and Treasury holdings have to clear at a price — SOFR. When something disrupts that equilibrium (a corporate tax-payment day that drains cash from the system, a large Treasury settlement that pulls collateral, a year-end balance-sheet constraint at major dealers), SOFR can spike dramatically. The September 2019 episode is the textbook example: SOFR jumped from ~2.2% to 5.25% intraday on September 17, 2019, before the Fed intervened with hundreds of billions of dollars of overnight repo operations through what's now the Standing Repo Facility (SRF).

How is SOFR different from the federal funds rate?

Federal funds is unsecured overnight lending between banks; SOFR is secured overnight lending (backed by Treasury collateral) across a broader population including dealers, money market funds, and corporates. In normal times, the two trade within a basis point or two of each other — same overnight horizon, same risk-free anchor (the Fed funds target range). In stressed times, they can diverge: SOFR spikes (collateral scarcity, dealer balance-sheet stress); Fed funds usually doesn't (banks have abundant reserves at the Fed, no need to borrow). The Fed targets the federal funds rate directly but uses both as inputs to its policy calibration.

What's the Standing Repo Facility (SRF)?

The SRF is a permanent Fed lending facility, established in 2021, that allows primary dealers (and some banks) to borrow dollars overnight against Treasury collateral at the upper bound of the federal funds target range. It exists specifically to put a ceiling on SOFR — if SOFR ever spikes above the SRF rate, dealers can borrow from the Fed at that rate and arbitrage SOFR back down. The SRF is, in effect, the lesson the Fed learned from September 2019: don't wait for a repo spike to set up emergency operations — keep a permanent facility ready.