CLO Basics and Leveraged Lending

Step 1: Annual Collateral Interest Income

Collateral Interest Income = Collateral Par × (SOFR + Weighted Average Loan Spread)

Using the $500.0m pool, SOFR of 4.00% (0.04) and a weighted average spread of 375 bps (0.0375):

Collateral Interest Income = $500.0m × (4.00% + 3.75%) = $500.0m × 7.75% = $38.75m

The collateral pool is the engine of the CLO: a portfolio of typically 150–300 senior secured, floating-rate leveraged loans to sub-investment-grade borrowers, most of them LBO term loans. Because both the assets and the CLO's own notes float over SOFR, the structure has almost no interest-rate mismatch — what matters is the credit spread the loans pay, not the level of rates. The 7.75% asset yield is the total cash the manager has available to distribute each year.

Step 2: Weighted Average Cost of CLO Debt and the CLO Arbitrage

Tranche Interest = Tranche Par × (SOFR + Tranche Spread)

Weighted Average Cost of CLO Debt = Total Tranche Interest / Total Rated Debt Par

Weighted Average Cost of CLO Debt = $26.95m / $445.0m = 6.06% (SOFR + ~206 bps)

CLO Arbitrage = Collateral Asset Yield − Weighted Average Cost of CLO Debt

CLO Arbitrage = 7.75% − 6.06% = 1.69% (169 bps)

Tranching is what makes this spread possible. By slicing $445.0m of claims into layers with different loss positions, the arranger can sell 62% of the deal to AAA investors (banks, insurers, Japanese and US institutional buyers) at only 150 bps over SOFR, even though every loan in the pool is rated single-B. The CLO arbitrage — the gap between what the assets earn and what the liabilities cost — is the raw material for the equity return. Note that the rated debt is 445 / 55 = 8.1x the equity, so the equity tranche is itself a highly levered instrument.

Step 3: Interest Waterfall and Residual Cash Flow to Equity

Residual to Equity = Collateral Interest Income − Senior Fee − Class A − Class B − Class C − Class D − Class E − Subordinated Fee

Using the $38.75m of collateral interest, the senior fee of 0.15% × $500.0m = $0.75m, the tranche interest from Step 2, and the subordinated fee of 0.35% × $500.0m = $1.75m:

Equity Cash Yield = Residual to Equity / Equity Par = $9.30m / $55.0m = 16.9%

The interest waterfall is the legal payment order written into the CLO indenture: cash flows strictly top-down, and no tranche receives a cent until everything senior to it has been paid in full. Fees are split deliberately — the senior fee sits above the AAA notes so the manager is always paid to keep servicing the deal, while the subordinated fee sits below the rated notes so the manager's economics are aligned with the equity. The equity holder is the residual claimant: it receives no fixed coupon, only what is left, which is why a 16.9% cash yield in a benign year can swing sharply in a stressed one.

Step 4: Overcollateralization (OC) Tests

OC Ratio (Class X) = Collateral Par / (Par of Class X + Par of All Tranches Senior to Class X)

Using collateral par of $500.0m, Class A + Class B par of $360.0m, and total rated debt of $445.0m:

Senior OC Ratio (Class A/B) = $500.0m / $360.0m = 138.9% vs. trigger of 125% → Pass

Junior OC Ratio (Class E) = $500.0m / $445.0m = 112.4% vs. trigger of 104% → Pass

Overcollateralization tests are the structural protection that justifies the ratings. They compare the par value of the loans backing the deal to the debt that has to be repaid; the cushion above 100% is the amount of collateral that could disappear before that tranche is impaired. If a test fails, the waterfall switches: cash that would have gone to the subordinated fee and equity is diverted to repay the Class A notes until the ratio is back above its trigger. Interviewers use OC tests to check whether you understand that CLO protection is dynamic — it is enforced continuously through cash diversion, not just set once at closing.

Step 5: Default Stress Case

Defaulted Par = Collateral Par × Default Rate

Principal Loss = Defaulted Par × (1 − Recovery Rate)

Using a 5.0% (0.05) default rate and a 60% (0.60) recovery:

Defaulted Par = $500.0m × 5.0% = $25.0m

Principal Loss = $25.0m × (1 − 0.60) = $10.0m

Lost Interest = $25.0m × 7.75% = $1.94m

Because losses are allocated bottom-up, the entire $10.0m principal loss is borne by the subordinated notes: equity par falls from $55.0m to $45.0m, and every rated tranche remains whole.

Stressed Residual to Equity = $9.30m − $1.94m = $7.36m → Stressed Equity Cash Yield = $7.36m / $55.0m = 13.4%

Stressed Collateral Par = $475.0m + $25.0m × 60% = $475.0m + $15.0m = $490.0m

Stressed Senior OC Ratio = $490.0m / $360.0m = 136.1% vs. 125% → Still passes

Stressed Junior OC Ratio = $490.0m / $445.0m = 110.1% vs. 104% → Still passes

This is the asymmetry at the heart of a CLO: cash is distributed top-down, losses are absorbed bottom-up. A 5% default year — roughly a recession-level rate for leveraged loans — wipes out 18% of the equity's par and cuts its cash yield by 3.5 points, yet the AAA investor sees no change at all and the OC cushions barely move. That is exactly why the senior tranches can be sold so cheaply and why, historically, no AAA CLO tranche has ever suffered a principal loss.

Final Results

• Collateral interest income: $38.75m (7.75% asset yield)
• Weighted average cost of CLO debt: 6.06% → CLO arbitrage of 169 bps
• Residual to equity: $9.30m → equity cash yield of 16.9%
• Senior OC ratio: 138.9% (trigger 125%); junior OC ratio: 112.4% (trigger 104%)
• 5% default stress: $10.0m loss borne entirely by equity, senior OC still 136.1%

Why this matters for private equity: CLOs buy roughly two-thirds of all newly issued institutional leveraged loans, which makes them the single largest source of LBO term-loan financing. When CLO arbitrage is healthy — asset spreads wide relative to AAA funding costs — new CLOs are created, demand for term loans B is strong, and sponsors can raise more debt at tighter spreads. When AAA spreads widen or arbitrage collapses (as in 2008 and 2022), CLO formation stalls, loan pricing gaps out, and the leverage available for buyouts falls with it.

Would you like to explore how a CLO's reinvestment period and prepayment behaviour change the equity return over the life of the deal?