Collateralized Loan Obligation
A collateralized loan obligation (CLO) is a structured credit security backed by a diversified pool of leveraged loans — typically floating-rate loans made to below-investment-grade corporate borrowers — divided into tranches with different risk and return profiles that are sold to institutional investors.
CLOs are the dominant buyers of leveraged loans in the U.S. credit market. The structure is created by a CLO manager — typically an asset management firm specializing in leveraged credit — which assembles a portfolio of 150 to 300 broadly syndicated loans made to non-investment-grade companies. The CLO vehicle issues multiple tranches of debt, ranging from senior AAA-rated notes through investment-grade mezzanine tranches down to BB-rated notes and an unrated equity tranche that absorbs the first losses from any portfolio defaults.
Each tranche receives interest and principal payments in strict priority order (the waterfall): senior debt holders are paid first from loan cash flows, with progressively junior tranches receiving residual cash flows after more senior classes are satisfied. The equity tranche, typically retained by the CLO manager or sold to specialized CLO equity investors, absorbs all credit losses before any impairment reaches the debt tranches. This structural subordination is what allows the senior tranches to achieve investment-grade or AAA ratings despite being backed entirely by loans to speculative-grade borrowers.
Because the underlying leveraged loans carry floating rates tied to SOFR plus a spread, CLO debt tranches also pay floating rates. This combination — investment-grade or near-investment-grade rated securities paying floating coupons — has made CLO tranches attractive to banks, insurance companies, and asset managers seeking higher yields than comparably rated corporate bonds without taking on interest rate duration risk.
CLO managers actively manage the loan portfolio during a reinvestment period, typically lasting three to five years after the CLO closes, buying and selling loans to manage credit quality and optimize returns for equity holders. After the reinvestment period ends, the CLO enters an amortization phase during which loan principal repayments are used to pay down CLO debt tranches in order of seniority.
The CLO market attracted regulatory scrutiny following the Dodd-Frank Act, which initially proposed including CLOs in risk retention requirements. After extensive litigation, courts ultimately exempted open-market CLOs from risk retention, allowing CLO managers to distribute all tranches without retaining a mandatory share. This outcome preserved the economics of the CLO market and supported its continued growth into one of the largest segments of the U.S. structured finance landscape.