Every lender has a temperament. Some barely move when the Fed shocks the market. Others swing violently — in both directions. Shock Beta is the first metric to measure it, validated across two opposite macro shocks using 8 years of HMDA data.
0 = rock stable across all conditions. 100 = maximum amplitude. Score = normalized average year-over-year denial rate movement, 2018–2025.
The refi objection — tested and dismissed. Could this just be product mix (refi-heavy lenders swinging with refi volume)? We ran the partial correlation controlling for each lender's 2021 refi share: the relationship barely moved (r = 0.946 → 0.935). The killer counterexample is Mr. Cooper — the highest refi exposure in the sample (0.99) with one of the lowest betas (22). Temperament is institutional, not compositional.
"Routing tells you where a lender stands today. Shock Beta tells you whether they'll still be standing there tomorrow."
If market conditions are shifting — Fed moves, rate spikes, credit tightening headlines — a high-beta lender's behavior from last quarter is a poor guide to next quarter. A borderline file that clears Freedom (beta 100) today may hit a wall in three months. The same file at Guild (beta 0) faces roughly the same odds in any weather. Stable-beta lenders are where you send files when timing is uncertain.
This is a historical data observation, not a recommendation to apply to or avoid any lender. Always consult a licensed mortgage professional.
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