A CLO is a special purpose vehicle (SPV) that issues multiple classes of debt and equity notes and uses the proceeds to buy a portfolio of leveraged loans — loans made to below-investment-grade companies, typically to finance private equity buyouts. The CLO manager selects and actively manages the loan portfolio; the SPV's investors receive cash flows from the loans, allocated in strict priority order from most senior to most junior.

The Capital Structure: AAA to Equity

A typical CLO issues six to eight tranches:

  • Class A (AAA): The most senior tranche, rated AAA by Moody's and S&P. This tranche is paid first from all loan interest and principal receipts. It typically represents 60–65% of the CLO's capital structure. Investors include money market funds, insurance companies, and bank treasury departments. Spread over SOFR: 120–170bp in normal markets.
  • Class B (AA): Second in priority. Represents about 10% of capital. Spread: 180–220bp.
  • Class C (A): Third in priority. About 6% of capital. Spread: 230–280bp.
  • Class D (BBB): The first "mezzanine" tranche that begins to face meaningful credit risk. About 5% of capital. Spread: 350–450bp.
  • Class E (BB): Higher risk. About 4% of capital. Spread: 600–800bp.
  • Class F (B): Very high risk. About 2% of capital. Spread: 900bp+.
  • Equity (first loss): The most junior piece — typically 8–10% of the capital structure. The equity tranche absorbs all losses before any rated tranche is impaired. In exchange, equity holders receive all excess cash flow after paying the rated tranches. Target equity returns are typically 12–18% IRR.

The Waterfall

All interest and principal payments received from the loan portfolio flow into the SPV and are distributed according to a strict priority of payments — the "waterfall." In simplified form:

  1. Senior fees (trustee, administrator, CLO manager senior fee)
  2. Class A interest
  3. Class B interest
  4. Overcollateralisation (OC) tests — if failed, divert cash to pay down senior notes
  5. Class C interest (if OC tests pass)
  6. Class D, E, F interest
  7. Subordinated CLO manager fee
  8. Equity residual cash flow

If losses in the loan portfolio trigger the OC tests (explained below), cash that would otherwise flow to junior tranches is diverted to repay the senior tranches instead — protecting the AAA and AA investors at the expense of the equity and mezzanine holders.

The CLO Manager

The CLO manager — typically a specialist credit asset management firm like Blackstone Credit, PGIM, or Ares — is responsible for selecting and managing the loan portfolio. The manager has discretion to buy and sell loans within the portfolio during the reinvestment period, subject to eligibility criteria: minimum average rating, maximum industry concentration, maximum single-name concentration, minimum diversity score.

The CLO manager earns a senior management fee (typically 15–20bp per annum on the CLO's assets, paid senior in the waterfall) and a subordinated fee (typically 30–40bp, paid junior — so it is only paid if the rated tranches are healthy). This fee structure aligns the manager's incentives with the rated note holders.

Ramp-Up and Reinvestment Period

When a CLO closes, the SPV has raised its capital but may not yet have invested all of it in loans. The ramp-up period (typically 3–6 months) is the time during which the CLO manager deploys the proceeds into the loan portfolio. During this period, uninvested cash earns a low return, which can drag on equity performance.

After the portfolio is fully ramped, the CLO enters the reinvestment period — typically three to five years — during which principal received from loan repayments is reinvested in new loans rather than returned to note holders. This allows the CLO to maintain its target leverage and keep investing even as older loans mature or are refinanced.

After the reinvestment period ends, the CLO enters its amortisation period: loan principal is no longer reinvested but is instead passed through the waterfall to repay the note tranches in order, starting with the most senior. Eventually, all rated tranches are repaid and the remaining portfolio value flows to the equity.

Overcollateralisation Tests

OC tests are structural safeguards that monitor whether the loan portfolio's value exceeds the outstanding balance of each tranche by a sufficient margin. A Class A/B OC test might require the portfolio par value to be at least 120% of the outstanding Class A and B notes. If the OC test fails — typically because loans have defaulted or been marked down below par — the waterfall redirects cash to repay the senior tranches rather than paying junior interest, restoring the OC ratio over time.

Risk Retention

Post-2008 securitisation regulations in both the US (Risk Retention Rule, 2016) and EU (Article 6 of the Securitisation Regulation) require CLO managers or sponsors to retain at least 5% of the CLO's economic risk. This "skin in the game" requirement was intended to prevent the originate-to-distribute model that contributed to the 2008 crisis. CLO managers typically retain the 5% by holding a portion of the equity tranche.

Key Terms

CLO (Collateralised Loan Obligation)
A structured vehicle that buys a portfolio of leveraged loans and issues tranched notes from AAA to equity, with each tranche absorbing losses in reverse order of seniority.
Waterfall
The strict priority of payments in a CLO — all cash flows from the loan portfolio are distributed top to bottom: senior fees, then AAA interest, then AA, and so on, with equity receiving whatever remains.
Reinvestment Period
The period (typically 3–5 years) during which the CLO manager can reinvest loan principal repayments in new loans rather than returning them to investors. Key to maintaining the CLO's leverage and yield.
Overcollateralisation (OC) Test
A structural test that checks whether the loan portfolio's par value exceeds the outstanding notes by a specified multiple. If failed, cash is diverted from junior tranches to repay senior notes until compliance is restored.
Leveraged Loan
A loan made to a below-investment-grade (typically private equity-backed) company. These loans are floating-rate, senior secured, and are the primary asset class held by CLOs.
Risk Retention
The regulatory requirement for CLO managers to retain at least 5% of the economic interest in a CLO — ensuring "skin in the game" and aligning manager incentives with investor outcomes.