themortgagellm^™

What it does

Gradient-boosting classifier rating the probability that a conventional conforming purchase-originated loan will be flagged as HomeReady — Fannie Mae's 3% down, 80% AMI income- limited affordable program that permits down-payment-assistance more flexibly than standard conventional. Trained on Fannie Single-Family Performance Data, 2018-2022 originations (5.5M purchase loans, primary residence only), tested on 2024-2025 (1.3M loans): OOT AUC 0.946. Isotonic-calibrated on 2023. Fair-lending AIR audit ACCEPTABLE across race (0.800), ethnicity (0.864), and sex (0.967) — well within the 4/5ths rule.

Why it matters. HomeReady is Fannie's flagship affordable-conventional product: 3% down, reduced MI pricing, income limits at 80% area median, community-second and DPA-flexible. Identifying likely-HomeReady borrowers at intake helps LOs route them to affordable-loan specialists earlier, tighten pricing quotes, and triage marketing spend. Capital-markets desks can use the pool-level aggregate to estimate HomeReady composition on incoming pipelines and price MSR strips accordingly — HomeReady loans prepay differently from standard conventional given the income-limit hold-in-place dynamics.

What it is NOT. This is a propensity signal for identifying likely HomeReady borrowers, NOT an underwriting determination and NOT a product-steering tool. HomeReady eligibility is verified by Desktop Underwriter — income limits, occupancy attestation, homebuyer education requirement, and other program-specific checks. If a lender used this score to route a borrower AWAY from HomeReady to protect origination fees, that would be illegal steering under ECOA. Position the score for opportunity, not gatekeeping.

Universe note. Only scores conventional conforming purchase originations against Fannie's SFP tape. Refinance loans, Freddie loans (use the Home Possible model), FHA/VA/USDA, jumbo, and investor loans are out of scope. Top features by importance: mi_pct (HomeReady gets reduced MI, so high MI% is a strong signal), upb (loan-size cap dynamic), cltv (community-second CLTV extension), dti (looser DTI overlay), msa (state HFA program overlap).

› Try it on the home page (Loan-level model scoring → HomeReady Propensity)

API connector

Programmatic access. Calibrated probability + risk band + operating recommendation in the response.

POST /api/score_homeready_propensity
Content-Type: application/json

{
  "fico": 720,                    // required (borrower FICO at issuance)
  "dti": 38,
  "ltv": 97,                      // HomeReady goes to 97% LTV
  "cltv": 105,                    // community-second allowed up to 105
  "upb": 320000,
  "mi_pct": 25,
  "fthb": "Y",                    // first-time homebuyer flag
  "state": "IL",
  "property_type": "SF",          // SF / PU / MH / CO / CP
  "units": 1,
  "channel": "R",                 // R=Retail, B=Broker, C=Correspondent
  "num_borrowers": 2,
  "loan_term": 360
}

Response includes homeready_probability, quantile band (P99 / P95 / P90 / P75 / P50 / P25 / P10), and a disclosure that this is a pre-DU heuristic. Not for steering.

Schema reference (request / response shape): GET /api/score_homeready_propensity/schema

Model metadata (training cohort, AUC, calibration): GET /api/score_homeready_propensity/info