The Width of the Cliff
Two loans can score identically today and be worlds apart in how fast they fall. One is safe until the takeout rate touches 7% and a cliff the moment it crosses; the other stays comfortable from 6% all the way to 8%. Same number today, opposite risk. This chapter is about reading the fragility a single-point score hides — the width of the ledge, not the spot you’re standing on.
Every exit read rests on an assumption you may not have noticed you were making: the takeout rate. When the Exit Gap lens tells you a loan refinances comfortably, it is telling you so at a particular assumed rate for the new loan. Change that assumption and the answer can change with it. A loan that clears at a 6.5% takeout and fails at 7% is carrying a fragility that the 6.5% score never shows — it looks exactly as healthy, on the page, as a loan that clears from 6% to 8% without flinching. The point estimate flattens them. The risk is in what the point estimate throws away: how much room there is on either side before the answer flips.
So you read the band, not the point. The Rate Shock view walks the takeout rate up in steps and re-solves the exit at each one, so you can watch precisely where a loan crosses from safe into cliff. A robust loan holds its footing across a wide range of rates — you can be wrong about the takeout by a full point and the conclusion survives. A fragile loan flips on a small move — a quarter-point of rate you didn’t foresee, and a loan you called healthy is suddenly underwater on its exit. The width of the safe band is the real measure of exit risk, and two loans with the same score today can have bands that differ by hundreds of basis points.
What makes one band narrow and another wide is structural, and worth knowing by feel. Leverage: a highly-levered loan has no cushion, so it flips fast; a conservatively-sized one absorbs rate moves before the exit breaks. Amortization: an interest-only loan exposes its entire balance at maturity, so it crosses sooner than one that has paid down. Vintage: loans written in the low-rate years face the largest repricing to get to today’s rates, so they sit closest to the edge — the 2021 cohort has the least room. Structure: a floating-rate loan feels every rate move immediately, where a fixed-rate loan’s danger is concentrated at its one maturity date. A read that stops at today’s number treats the fragile and the robust as equals; the band is where the difference lives.
And because the drivers of fragility are structural, fragility clusters — which is exactly what makes it dangerous in a trust. Narrow bands concentrate by vintage and by structure, so a deal loaded with one vintage of low-rate, interest-only paper doesn’t hold a handful of independent cliff loans; it holds a cohort that flips together the moment the takeout rate crosses their shared edge. Reading the width per loan rolls straight up into reading which trusts and which vintages are one rate move from a wave of cliffs at once. The Vintage lens is where that concentration becomes visible — the same fragility, read at the level of the book instead of the loan.
The discipline is one sentence: never accept a single-point exit read. A loan that is “fine” only at today’s exact rate assumption is not fine — it is fine conditional on an assumption, and the condition is the risk. Ask the band. The loan worth worrying about is not always the one that scores worst today; it is often the one that scores fine today and sits a quarter-point from the edge, because that is the one the market — and a careless reader — will call safe right up until the day it isn’t.