Net Interest Income

The difference between the revenue a bank earns from its interest-bearing assets and the expenses associated with paying its interest-bearing liabilities.

Net Interest Income (NII) is the primary revenue driver for traditional commercial banks and thrift institutions. It represents the gross spread earned by a financial institution on its core lending and borrowing activities. Specifically, it is the difference between the interest income generated from assets like mortgages, commercial loans, and government securities, and the interest expenses paid out to depositors and wholesale funding providers. Investors analyze NII to evaluate a bank's core earning power and its sensitivity to changing interest rate environments. When central banks adjust benchmark interest rates, both the yields on a bank's assets and the costs of its liabilities shift. A bank with a large base of low-cost, sticky retail deposits can often keep its funding costs low even as it charges higher rates on new loans, leading to an expansion in NII. However, NII can be highly volatile during rapid interest rate cycles. If interest rates rise quickly and depositors demand higher yields (a concept known as high deposit beta), a bank's interest expenses may rise faster than its loan yields, squeezing its margins. Conversely, in a falling rate environment, loan yields may drop faster than deposit costs, also hurting NII. Investors must look at NII alongside credit quality, as a bank might artificially boost NII by taking on riskier, higher-yielding loans that carry a greater risk of default.

Bank A earns $15.5 billion in interest from its loan portfolio and debt securities, and pays out $3.5 billion in interest to its depositors and bondholders. Its Net Interest Income is calculated as $15.5 billion - $3.5 billion = $12.0 billion.