The LIBOR-OIS Spread as a Stress Gauge
LIBOR embeds the risk that a bank might not survive to repay an unsecured loan, while OIS is close to risk-free; the gap between the two spent decades near zero and then blew out to hundreds of basis points exactly when the market started doubting bank solvency.
Prerequisites: OIS Discounting and Multi-Curve Frameworks, The Federal Funds Market and the Effective Rate
Two three-month interest rates, both quoted every day, both supposedly measuring "the cost of short-term money." Most of the time they sit almost on top of each other. Then, in a crisis, they can rip ten times further apart in weeks. The gap between them — LIBOR minus OIS — is one of the oldest and most reliable stress gauges in finance, precisely because the two rates are built to measure different things.
LIBOR was an unsecured interbank lending rate, so it embeds a bank credit-risk premium — the chance the borrowing bank doesn't survive the loan's term. OIS reflects the expected path of the risk-free policy rate, with essentially no credit risk. Widening LIBOR-OIS spread means the market is pricing rising bank default risk, not a change in monetary policy.
Why the two rates normally sit close together
In calm conditions, the market assigns almost no probability that a major bank fails within three months, so the credit-risk premium embedded in LIBOR is tiny — a handful of basis points. LIBOR and OIS then track each other closely, both essentially reflecting where the policy rate is expected to sit. The moment that assumption breaks down — a bank's solvency becomes genuinely uncertain — lenders in the unsecured interbank market start demanding real compensation for the chance of not being repaid, while OIS, tied to the policy rate rather than any specific bank's credit, barely moves. The spread between them opens up as a direct read of "how worried is the market about bank credit risk," stripped of the confound of where rates are generally headed.
Worked example
In normal conditions, 3-month LIBOR is 5.35% and 3-month OIS is 5.25%, a spread of 10 basis points — mostly reflecting a small structural credit premium and term-liquidity preference, nothing alarming. During the acute phase of the 2008 crisis, 3-month USD LIBOR-OIS reached roughly 3.64%, a spread of 364 basis points. A bank borrowing $100 million unsecured for three months at the crisis-level spread paid an extra , i.e. $885,000 in interest over that quarter purely as compensation for counterparty risk, compared to what it would have paid at the normal 10bp spread.
What this means in practice
Because LIBOR itself is being phased out in favor of SOFR (which has no embedded bank credit risk at all), the pure LIBOR-OIS spread is now mostly a historical and analytical tool rather than a live daily indicator; its conceptual successor uses credit-sensitive benchmarks like Term SOFR or Bloomberg's BSBY spread against OIS to capture the same signal.
A widening LIBOR-OIS spread reflects perceived bank credit risk specifically — it is not a general-purpose recession or equity-market stress indicator, even though it often co-moves with both during systemic crises. Read it as a funding-market gauge first.
Related concepts
Practice in interviews
Further reading
- Michaud & Upper, 'What Drives Interbank Rates? Evidence from the LIBOR Panel'
- Taylor & Williams, 'A Black Swan in the Money Market'