Rate Sensitivity Modeling for Banks
Rate sensitivity modeling is how banks measure what would happen to their earnings and balance sheet value if interest rates moved by a specific amount. The results show up in SEC filings as tables projecting changes to net interest income (NII) and economic value of equity (EVE) under standardized rate shocks.
The Two Main Measures
NII sensitivity estimates how the bank's interest income minus interest expense would change over the next 12 months if rates shifted immediately. A bank reporting "+200bp: NII -4.2%" expects its annual net interest income to drop 4.2% if rates rise 200 basis points. This is the near-term earnings measure.
EVE sensitivity takes a longer view. It estimates how the present value of all the bank's assets minus liabilities would change under the same rate shock. EVE captures the full balance sheet impact, including changes in the market value of long-duration loans and securities that don't immediately affect earnings. A bank can show modest NII sensitivity but significant EVE sensitivity if it holds a large portfolio of long-term fixed-rate assets.
How to Read the Disclosures
Most banks present a table with columns for rate changes of -100, -200, +100, +200, and sometimes +300 basis points. Look for asymmetry. A bank that benefits significantly from rising rates but suffers only modestly from falling rates has positioned itself for a particular outcome. Equal sensitivity in both directions suggests a more neutral posture.
Compare the numbers across reporting periods. If a bank's sensitivity to rising rates doubled over the past year, management made a deliberate or accidental bet. The 10-K management discussion section usually explains why the position changed.
Limitations to Keep in Mind
These models assume rates move instantly and in parallel across all maturities, which never actually happens. They also rely on assumptions about how quickly depositors will move money in response to rate changes (deposit betas) and how fast borrowers will refinance loans (prepayment speeds). Different assumptions produce very different results, and banks choose their own assumptions.
Two banks with identical balance sheets could report different sensitivity numbers simply because one uses more conservative behavioral assumptions. When possible, compare banks using the same methodology and time frame rather than mixing approaches.
Related Articles
- Duration Gap Analysis for Banks — Duration gap is the underlying driver of rate sensitivity results
- Net Interest Income Simulation — Dynamic NII simulation builds on static sensitivity modeling
Related Metrics
- Net Interest Margin (NIM) — NII sensitivity directly measures projected NIM changes under rate shocks
- Cost of Funds — Funding cost assumptions are a key input to rate sensitivity models