Net interest margin (NIM): Net interest margin is what a bank keeps on the spread between what it earns on its assets and what it pays for its funding, as a percentage of the assets that earn.
How it is calculated
Net interest income over average earning assets, annualized. Earning assets come from Schedule RC as total assets less noninterest bearing cash, premises, other real estate owned, intangibles and other assets, with the allowance for credit losses added back so loans enter net of unearned income only.
Formula
NIM = annualized net interest income / average earning assets
What banks reported in Q2 2026
Across every bank that filed for Q2 2026, the median net interest margin was 3.83%, with the middle half between 3.35% and 4.33%. The right comparison is almost always the row for the bank’s own size rather than the industry line.
| Bank size (total assets) | Bottom quartile | Median | Top quartile |
|---|---|---|---|
| Under $100M | 3.37% | 3.88% | 4.50% |
| $100M - $300M | 3.42% | 3.93% | 4.42% |
| $300M - $1B | 3.41% | 3.88% | 4.30% |
| $1B - $3B | 3.26% | 3.69% | 4.11% |
| $3B - $10B | 3.21% | 3.64% | 4.06% |
| $10B - $100B | 3.18% | 3.57% | 3.92% |
| Over $100B | 2.07% | 3.07% | 3.70% |
Source: BankingLens, computed from FFIEC call reports for the quarter ending June 30, 2026. Quartiles are calculated across the full population of filing banks in each size band, not sampled. Non-insured non-deposit trust companies are left out of every statistic: they take no deposits and make no loans, so a margin or a funding cost computed for them has no meaning.
How to read it
NIM is the cleanest single read on the spread business: borrow at one rate, lend at a higher one, keep the difference. Most banks sit between 3% and 4.5%. Above 5% means the loan book earns more than a commercial book does, usually consumer, card or specialty credit, and above 8% almost always means a specialty charter rather than a bank with branches.
The common mistake. Treating a wide margin as a healthy bank. A spread that is being eaten by overhead or by credit provisions reads fine here and badly in ROA, so the two have to be read together.
Go deeper
- What is a good net interest margin for a bank?
- BankingLens pricing and what a subscription adds: percentile rank against the bank’s own FFIEC peer group, fourteen quarters of trend, and the flags an examiner reaches for first.
See also. Net interest income, Net interest spread, Cost of funds, Yield on earning assets, Earning assets.
Every figure on this page is computed from FFIEC call reports for the quarter ending June 30, 2026 and is not modeled, estimated or sampled. This page is generated by _tools/seo/build_glossary.mjs and carries no figure that was typed in. See our methodology and disclaimer. Definitions are general guidance, not regulatory or investment advice.