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 | 14,791.64 | 14,791.64 | 443,757.58 | 443,757.58 | 0.01 |
| 1-AX | 21,217.27 | 21,217.29 | — | — | 0.02 |
| 2-A1 | 42,606.71 | 42,607.41 | 2,680,785.28 | 2,680,785.28 | 0.71 |
| 2-AX | 41,400.88 | 41,401.53 | — | — | 0.65 |
| B-1 | 13,288.77 | 13,288.36 | 347,789.33 | 347,789.33 | 0.41 |
| B-2 | 8,859.18 | 8,858.91 | 231,859.55 | 231,859.55 | 0.27 |
| B-3 | 5,993.44 | 5,993.25 | 156,858.27 | 156,858.26 | 0.19 |
| B-4 | 4,429.59 | 4,429.45 | 115,929.78 | 115,929.78 | 0.14 |
| B-5 | 12,531.74 | 12,531.37 | 0.00 | 0.00 | 0.37 |
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.