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 | 37,364.56 | 37,364.18 | 1,327,702.21 | 1,327,702.21 | 0.39 |
| 1-AX | 54,720.97 | 54,720.35 | — | — | 0.62 |
| 2-A1 | 108,939.92 | 108,939.92 | 1,386,418.70 | 1,386,418.70 | 0.00 |
| 2-AX | 107,004.37 | 107,004.31 | — | — | 0.06 |
| B-1 | 25,131.32 | 25,131.63 | 97,915.63 | 97,915.63 | 0.31 |
| B-2 | 16,754.21 | 16,754.42 | 65,277.09 | 65,277.09 | 0.21 |
| B-3 | 11,334.61 | 11,334.74 | 44,161.44 | 44,161.44 | 0.14 |
| B-4 | 8,377.11 | 8,377.21 | 32,638.54 | 32,638.54 | 0.11 |
| B-5 | 12,654.91 | 12,655.20 | 0.00 | 0.00 | 0.29 |
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.