FICO's mortgage grip is a government rule. One rival cleared, the stock fell 19% in a day.

Your FICO score is the three-digit number, 300 to 850, that decides whether you get a mortgage and at what rate. It is made by a single company, Fair Isaac Corporation. Not the government, not the banks. One company's formula sits at the center of American lending.

The moat is the rule itself. Loosen it and it falls.: The rule · Fannie & Freddie require Classic FICO · Mandatory demand · Every loan in the $13T market buys a score · Pricing power · Raises the price at will: +27% in a quarter · The crack · VantageScore cleared; stock -19% in a day

Its grip on the $13 trillion mortgage market was never really about better math. Fannie Mae and Freddie Mac, which buy most US mortgages, required lenders to use the Classic FICO score. That made it mandatory by rule, so FICO could raise its per-score price almost at will: its Scores revenue jumped 27% in one quarter, mostly on price. The proof it was the rule and not the formula came in July 2025, when regulators cleared a rival, VantageScore, and FICO's stock dropped about 19% in a single day.

The strongest moat is a rule that names your company. Loosen the rule, lose the moat.