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CFA® Level I · Fixed Income · free lesson
Asset-Backed Security (ABS) Instrument and Market Features
Beyond mortgages, securitization funds car purchases, credit card spending, student loans and corporate leveraged loans. Each asset type produces cash flows with its own shape and risks, and each deal layers protections on top. This module explains how ABS are credit-enhanced, how amortizing auto loan ABS differ from revolving credit card ABS, and how collateralized debt obligations, including today's large CLO market, turn pools of corporate debt into tranches.
What you will learn
1. Describe the internal and external credit enhancement mechanisms used in asset-backed securities and calculate the protection they provide.
- Internal enhancement: subordination, overcollateralization, excess spread, reserve accounts.
- Excess spread = pool interest - note interest - servicing and other fees; it absorbs losses each period.
- External enhancement: guarantees, bond insurance, letters of credit.
- External enhancement exposes investors to the guarantor's credit: third-party risk.
- Total enhancement for a tranche = subordination + OC + reserves, compared with stressed losses.
2. Describe the cash flows, prepayment behaviour and risks of ABS backed by amortizing assets, using auto loan ABS as the main example.
- Amortizing ABS pass through interest, scheduled principal and prepayments each period.
- Auto loan prepayments come from car sales, write-offs and refinancing; they are not very rate-sensitive.
- Prime and subprime pools differ sharply in losses and in required credit enhancement.
- Recoveries depend on used-car prices; lease ABS also carry residual value risk.
- Short, granular, predictable cash flows suit short-duration investors.
3. Describe the structure of credit card receivable ABS, including the revolving and amortization periods, excess spread and early amortization triggers.
- Credit card ABS are non-amortizing; a master trust issues many series from one pool.
- Revolving period: investors get interest only; principal buys new receivables.
- Amortization or accumulation period: principal is returned to investors.
- Excess spread = portfolio yield - charge-offs - note coupon - servicing.
- Early amortization triggers (negative excess spread, originator insolvency) protect investors but cut off issuer funding.
4. Describe the structure and economics of collateralized debt obligations, including collateralized loan obligations, and calculate the return to the equity tranche.
- CDOs are backed by debt portfolios; CLOs (leveraged loans) are the largest segment.
- An active collateral manager runs the portfolio within eligibility and diversification rules.
- The equity tranche earns the residual spread and absorbs first losses: a leveraged position.
- OC and IC tests divert cash from junior to senior tranches when breached.
- Synthetic CDOs reference a portfolio through credit default swaps.
Module at a glance
- Internal credit enhancement: subordination, overcollateralization, excess spread and reserve accounts.
- External enhancement (guarantees, wraps, letters of credit) adds third-party risk, as the 2008 monoline downgrades showed.
- Amortizing ABS such as auto loans pass through interest, scheduled principal and prepayments.
- Auto loan prepayments are driven by car sales and write-offs, not refinancing; lease ABS add residual value risk.
- Credit card ABS use master trusts with revolving periods; investors get interest only until amortization.
- Early amortization triggers protect investors but cut off the originator's funding.
- CDOs and CLOs pool debt under an active manager; equity is a leveraged bet on the excess spread, protected by OC and IC tests.
This free module has 4 lessons, 13 practice questions with full explanations.