What it means
SOFR is built from real overnight repurchase agreement trades, where one party sells Treasury securities and agrees to buy them back the next day, which is effectively secured borrowing. Because it comes from a large volume of genuine transactions rather than estimates submitted by banks, it is far harder to manipulate than the rate it replaced.
For borrowers it matters because it sits directly in the interest cost of most new commercial loans. A facility priced at SOFR plus 200 basis points moves with the benchmark, so a one percentage point rise in SOFR raises the interest bill by one percentage point on the drawn balance.
In practice lenders rarely use the raw overnight figure for a loan that pays quarterly. They use Term SOFR, a forward-looking rate for one, three, six or twelve months, or an averaged compounded SOFR calculated over the interest period, and the credit agreement specifies exactly which.
The nuance that surprises people transitioning from LIBOR is that SOFR is a secured, near risk-free rate while LIBOR included bank credit risk. That makes SOFR structurally lower, which is why transition agreements added a credit spread adjustment so that converted loans kept broadly the same economics.
SOFR also behaves differently at stress points because it reflects collateral markets rather than bank funding fears. It can spike briefly around quarter ends when demand for cash in repo markets tightens, which is one reason many contracts use an average rather than a single day's print.
In practice
Real-world examples.
Example
A mid-market manufacturer refinances a $30,000,000 term loan that had been priced off LIBOR. The new agreement uses three-month Term SOFR plus a margin and includes a credit spread adjustment so the effective cost is close to the old facility on day one.
Example
A property investor with a floating SOFR mortgage buys an interest rate cap that pays out if three-month SOFR exceeds 5.50%. The cap premium is treated as an insurance cost against the rate rising beyond what the rental income can service.
Example
A treasury team preparing a three-year cash forecast models three SOFR paths: unchanged, up 150 basis points and down 100 basis points. The spread of forecast interest costs tells the board how much headroom the covenant package really has.
Think of it
“SOFR is the new US benchmark rate-based on Treasury repo transactions.
Formula
Calculation
Interest for a period = principal x (SOFR + margin) x days in period / 360, using the actual/360 day count that most US dollar loans apply.
Take a $5,000,000 revolving facility priced at three-month Term SOFR plus 200 basis points, drawn in full for a 90-day interest period. If Term SOFR sets at 4.30%, the all-in rate is 4.30% + 2.00% = 6.30%. Annual interest at that rate would be $5,000,000 x 6.30% = $315,000, and for 90 days the borrower owes $315,000 x 90 / 360 = $78,750.
Now suppose SOFR resets at 5.30% for the following quarter. The all-in rate becomes 5.30% + 2.00% = 7.30%, annual interest would be $5,000,000 x 7.30% = $365,000, and the quarterly payment is $365,000 x 90 / 360 = $91,250. The one percentage point move has added $91,250 - $78,750 = $12,500 to a single quarter's interest, which is the exposure a borrower would consider hedging.Case study
Seen in the real world.
Ardenmoor Foods is an illustrative, fictional ready-meals producer with a $24,000,000 floating-rate facility priced at Term SOFR plus 250 basis points. Its board had grown used to a period of very low benchmark rates and treated interest as a small, stable line in the forecast.
When SOFR rose sharply, the all-in rate moved from roughly 3.00% to roughly 7.50%, and annual interest on the drawn balance climbed from about $720,000 to about $1,800,000. That extra $1,080,000 was more than the company's planned capital spending for the year, and the interest cover covenant came uncomfortably close to breaching.
The illustrative lesson is that floating-rate debt is an unhedged forecast assumption unless you treat it as one. Ardenmoor subsequently fixed half the balance with an interest rate swap, accepting a slightly higher expected cost in exchange for a payment it could actually plan around.
Watch out
Common mistakes.
- Treating SOFR as a fixed rate. It is a daily benchmark that moves with market conditions, so a loan priced off it has a variable interest cost by design.
- Comparing a SOFR margin directly with an old LIBOR margin. SOFR excludes bank credit risk and is structurally lower, so a like-for-like comparison needs the credit spread adjustment included.
- Not reading which version the credit agreement uses. Daily simple SOFR, compounded SOFR in arrears and Term SOFR can produce noticeably different interest for the same period.
Questions
People also ask.
Why did LIBOR need replacing?
It relied on banks estimating rates rather than reporting real trades, which left it open to manipulation and to becoming unrepresentative as the underlying market shrank.
Does SOFR apply outside the United States?
No, it is the US dollar benchmark; other currencies use their own successors such as SONIA in sterling and ESTR in euros.
How can a borrower protect against SOFR rising?
Common tools are an interest rate swap to fix the rate, a cap that limits the maximum, or simply repaying floating-rate debt faster.
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