Capital Markets & Portfolio Analytics

MSR Valuation Engine

Proprietary 774,770-formula engine reverse-engineering MIAC's WinOAS methodology to achieve exact-match valuation.

Timeline: January 2026 · PorchPass LLC
774,770
Dynamic formulas
$50K+/yr
Vendor dependency eliminated
13
Parameters reverse-derived
42x
Formula coverage increase

PorchPass was paying MIAC Analytics — the industry-standard MSR valuation provider — for monthly portfolio valuations using their proprietary WinOAS 4.4.4 methodology at $50K+ per year.

Nick built an internal MSR Valuation Engine by systematically reverse-engineering 18+ MIAC output files, decomposing the WinOAS methodology and mapping 6 revenue components and 8 cost components. Through iterative parameter calibration, he reverse-derived 13 undisclosed MIAC parameters — including conditional default rates, voluntary prepayment rates, discount rates, and servicing cost assumptions — achieving an exact-match 75.25 basis point valuation.

During the rebuild, Nick discovered 2,756 hardcoded values in the prior architecture and rebuilt from 18,000 to 771,831 formulas — a 42x increase in formula coverage — ensuring 100% dynamic recalculation. The final engine performs 100-loan x 300-month DCF analysis with monthly execution in under 10 minutes, 2 manual steps, zero VBA, and pure formula cascades.

ExcelopenpyxlPythonNumPyDCF ModelingOAS Analysis
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