1-Month LIBOR Explained: What Homebuyers and Real Estate Investors Should Know

While LIBOR once was one of the world’s most widely used interest benchmarks, it has been phased out for most major currencies and tenors. USD LIBOR was published until June 30, 2023, after which official LIBOR settings were discontinued. As a result, one month LIBOR no longer functions as a live published rate for new contracts in the traditional sense. However, in some legacy financial contracts a synthetic 1-month LIBOR may still be referenced temporarily under specific regulatory arrangements.

If you’re preparing to buy and considering adjustable-rate financing, many lenders now base adjustable interest rates on benchmarks like SOFR rather than the old one month LIBOR. However, older adjustable-rate loans or legacy financial products you encounter in secondary markets might still reference the 30-day LIBOR or related fallback rates. It’s important to ask your lender what index your loan uses and how interest is calculated.

This benchmark was calculated daily by surveying a panel of major banks about the rate at which they would lend unsecured U.S. dollar deposits to each other for a 30-day term. The average of these responses produced the published one month LIBOR — a daily snapshot of short-term interbank lending costs.

Monthly historical data show that the one-month LIBOR rate has fluctuated widely over decades, reflecting interest rate cycles and economic conditions: In the early 1990s, the rate was generally around 8–9%. After the 2008 financial crisis and into the 2010s, LIBOR rates declined as global interest rates fell. Before its discontinuation, the one month LIBOR was much lower than in past cycles, influenced by low-rate environments. This long-term trend — the one month LIBOR history — highlights how benchmark interest rates reflect broader macroeconomic forces.

For legacy contracts that reference 1-month LIBOR, financial markets have developed fallback provisions. These specify alternative reference rates (often SOFR-based) when LIBOR is not available. These fallbacks help ensure that contractual interest calculations continue smoothly, even after the traditional publication of LIBOR ceased.

Because of concerns about reliability and market manipulation in the LIBOR process, regulators and market participants transitioned to alternative reference rates. In the U.S., the Secured Overnight Financing Rate (SOFR) has become the preferred benchmark for dollar-denominated loans and derivatives. SOFR is based on actual transactions in the overnight repurchase market and is considered more robust than traditional LIBOR.

The 1-month LIBOR is the average interest rate at which major global banks lend U.S. dollars to one another for a one-month period in the London wholesale money market. It’s one of several LIBOR tenors that historically served as a benchmark for short-term borrowing costs. The term 30-day LIBOR simply refers to this same rate measured over a 30-day maturity.

Because 1-month LIBOR as a traditional published benchmark has been discontinued, there isn’t a current live 1-month LIBOR rate in the classic sense after June 2023. Instead, market participants now commonly use alternative reference rates — and some synthetic LIBOR fixes serve as limited fallbacks where contracts explicitly reference them.

Traditionally, the one month LIBOR has been used as a reference rate for setting adjustable interest rates on loans and financial instruments — from adjustable-rate mortgages to business financing and derivatives. That means changes in this rate could influence how much interest you pay on some kinds of borrowing tied to it.

Before its phase-out, one month LIBOR mattered because it represented a key short-term borrowing cost among banks and a benchmark lenders used to price loans and adjustable rate products. Although the traditional LIBOR era has ended, understanding one month LIBOR is still useful because many financial products issued before 2023 reference it in legacy contracts.