Updated May 2026. This page does not forecast rates; it explains where public data lives and how to use it in household stress tests.
Why “history” matters for ARMs
ARM economics are path-dependent: the relevant risk is not “average rates over decades,” but your reset schedule, caps, margin, and whether a higher fully indexed payment clears DTI and reserves after life shocks.
Authoritative public series (interpretation, not trading advice)
- Freddie Mac PMMS — weekly primary mortgage market survey of lenders; useful for long-run fixed-rate context. freddiemac.com/pmms
- Federal Reserve H.15 — selected Treasury and policy-sensitive yields; helps explain index environments that feed many ARM formulas. federalreserve.gov/releases/h15
| Series | What it approximates | Typical use in household modeling |
|---|---|---|
| PMMS | Surveyed offered rates on common fixed products | Benchmarking fixed quotes vs “headline” market |
| H.15 | Benchmark yields (e.g., Treasuries) | Reasoning about index direction for ARMs tied to published indexes |
Translate an index move into “payment shock” language
Work from your note disclosures: index + margin, first adjustment cap, periodic cap, lifetime cap. The operational article is ARM cap structure; the product comparison is fixed vs adjustable trade-offs.
Fixed-rate “historical regret” is refinance-shaped
Fixed borrowers who want market-downside capture usually need a refinance or aggressive prepay—there is no in-note coupon reset. Price that path with break-even math.