Waterfall Forensics
We ran the contract forward for eight years. It matched to the penny.
Sequoia Mortgage Trust 2013-1: deconstructed from its prospectus into an executable encoding, then replayed against every monthly distribution the trustee ever reported — 93 periods, February 2013 through final termination.
$363M
of actual distributions reproduced
99.7%
of 2,139 comparisons within $1
$0.08
worst principal delta, ever
Every period, every class — computed from the contract vs. reported by the trustee
| Class | Interest computed | Interest reported | Principal computed | Principal reported | Δ |
|---|---|---|---|---|---|
| 1-A1 | 124,735.67 | 124,735.67 | 462,158.26 | 462,158.26 | 0.01 |
| 1-AX | 184,473.82 | 184,473.88 | — | — | 0.06 |
| 2-A1 | 268,929.07 | 268,929.07 | 350,943.81 | 350,943.81 | 0.01 |
| 2-AX | 271,347.12 | 271,347.13 | — | — | 0.01 |
| B-1 | 29,892.12 | 29,892.12 | 26,329.31 | 26,329.31 | 0.00 |
| B-2 | 19,928.08 | 19,928.08 | 17,552.87 | 17,552.87 | 0.00 |
| B-3 | 13,481.80 | 13,481.80 | 11,874.92 | 11,874.92 | 0.00 |
| B-4 | 9,964.04 | 9,964.04 | 8,776.44 | 8,776.44 | 0.00 |
| B-5 | 12,789.32 | 12,789.25 | 0.00 | 0.00 | 0.07 |
drag through 93 distribution dates — Δ is the summed absolute difference between the contract-computed and trustee-reported figures for the period
Or see all 93 periods at once: the tie-out heatmap ›
How
The governing documents are deconstructed into a provenance-linked encoding — every waterfall step, trigger, and floor provision cites the clause that defines it. A deterministic interpreter executes that encoding, period by period, against the collateral cashflows the trustee reported. State rolls forward on computed values only; an error anywhere would compound and surface. It doesn't.
The same engine then runs Monte Carlo counterfactuals — what should have happened under different prepayment, default, or servicing behavior — and exports the whole model as readable Python your own analysts run and defend. Every encoding is open to clause-by-clause verification, and every verification lands in an append-only ledger.