Module 27
ABS: consumer & specialty credit
Asset-backed securities are the securitization of everything else: auto loans, credit-card receivables, student loans, equipment leases — and an “esoteric” wing that packages aircraft leases, whole-business royalties, even data-center revenues. Compared with mortgages the structures are short and clean: an auto deal amortizes down in a few years as borrowers make car payments; a card deal is revolving, recycling repayments into new receivables until a scheduled wind-down. Every deal is tranched into senior and subordinate bonds and throws off excess spread — the gap between what the loans yield and what the bonds cost.
Three things drive risk:
- Consumer credit performance — losses and delinquency roll-rates. This is macro: jobs, wages, gas prices.
- Deal structure — how much subordination sits beneath you, the reserve account, and (on cards) early-amortization triggers that wind the deal down if performance deteriorates.
- Collateral-specific behavior — used-car values for autos, payment rates for cards, servicer quality everywhere.
The workhorse forecasting tool is roll-rate analysis. A loan doesn't default overnight — it rollsthrough stages: current → 30 days delinquent → 60 → 90+ → charge-off. Each transition happens at a fairly stable rate, so multiplying the stage-to-stage roll rates turns today's early delinquencies into a loss pipeline you can see coming months ahead. Rising 30-day buckets are tomorrow's charge-offs.
Those losses then meet the deal's defenses bottom-up: excess spread absorbs them first, then the reserve account, then subordination. The senior tranche is impaired only if losses eat through all three — which is why senior ABS sailed through recessions that wrecked the underlying borrowers.
Run the pipeline yourself below.
🎛 Roll-rate lab
Net annual loss
1.43%
charge-offs after recoveries
Enhancement
8.0%
loss-absorbing cushion
Cushion
+6.57%
enhancement − net loss (1y)
Senior investors protected. Over a one-year horizon the roll-rate pipeline produces 1.43% of net losses — comfortably inside the 8.0% of enhancement. Excess spread absorbs losses first, then the reserve account, then subordination; the senior tranche never feels it.
The roll-rate pipelinemultiplies stage-to-stage transition rates — share going 30+ delinquent, then 30→60, 60→90+, 90+→charge-off — to project gross losses months before they hit; recoveries reduce them to a net loss rate. The comparison against enhancement is a simplified one-year snapshot: real deals model this month by month through a cashflow engine with triggers. Educational tool — not investment advice.
How the roll-rate pipeline is computed
Chain the transition rates together: of the pool that goes 30+ delinquent in a year, some fraction rolls to 60, of those a fraction rolls to 90+, and of those a fraction charges off. Recoveries (repossessed cars, collections) claw some back:
gross charge-offs = delinquent% × roll(30→60) × roll(60→90+) × roll(90+→CO) net loss = gross charge-offs × (1 − recovery) cushion = enhancement − net loss
With the lab's defaults: 8% × 50% × 60% × 70% = 1.68% gross, and at a 15% recovery about 1.43% of net losses — against 8% of enhancement, a wide cushion. The comparison is a simplified one-year snapshot; real analysis runs it monthly through a cashflow engine, where excess spread replenishes each period and triggers can redirect cash.
The takeaway:ABS is consumer and specialty credit in securitized form — shorter and more self-amortizing than mortgages, with performance tracked through delinquency roll-rates and measured against the deal's enhancement.
Things to try
- • Double the 30+ delinquency share (a recession) and watch net loss scale linearly — the pipeline is multiplicative, so early-stage deterioration flows straight through.
- • Push every roll rate toward its maximum. Even with modest delinquencies, sticky late-stage rolls produce serious losses — cure rates matter as much as inflows.
- • Set recovery to 60% (strong used-car market) vs 0% (unsecured cards) — the same charge-offs produce very different net losses. That's why card deals carry more enhancement.
- • Find the delinquency level where your cushion goes red, then ask: would you have seen the 30-day bucket rising months before that happened? That's the point of roll rates.