Finding
From Q2 2025 to Q2 2026, quarterly domestic deposit interest expense falls by $5.012 billion in the screened cohort. Balance growth adds $5.242 billion, interest-bearing mix adds $0.057 billion and the proxy-rate component subtracts $10.310 billion. The contributions reconcile to the total.
Why it matters
Use the breakdown to frame a treasury pricing review. Account-level rates, renewal dates and customer behavior are needed before assuming a rate cut will save money after attrition and replacement funding.
Who could use this
Bank treasury and finance teams reviewing balance growth, interest-bearing mix and pricing pressure.
Data and scope
A pinned FDIC panel of 48,814 bank-quarters across eleven dates. The matched screen retains 4,018 banks and 91% of latest domestic deposits.
How the analysis works
Quarterly/YTD reconciliation and deposit-stock checks precede an exact three-factor Shapley attribution. Six replacement orders allocate interactions symmetrically. Cohort screens and hypothetical attrition scenarios test sensitivity.
Limits of the evidence
The proxy rate is derived from endpoint-average balances and absorbs composition and timing effects. It is not a quoted product rate or causal deposit beta. Certificate matching and a growth screen do not fully remove acquisition effects.