Unitranche, Second-Lien, Mezzanine: Beyond TLB

Introduction

Beyond the standard Term Loan B, the leveraged finance product set includes three structurally distinctive debt instruments that fill specific roles in the capital structure: unitranche, second-lien secured loans, and mezzanine debt. Each product has its own pricing economics, structural mechanics, and typical use cases, and a leveraged finance banker covering sponsor and corporate clients needs to be fluent in all three to advise on optimal capital structures.

This article walks through the three products in detail. The framing is from the IBD DCM banker's seat, with leveraged finance origination as the principal coverage point and direct lending platforms as the principal counterparties on most of these specialized products.

Unitranche is the signature private credit product: a single first-lien senior secured tranche combining senior plus mezzanine economics into one loan with a blended coupon. The structure features a 5-7 year bullet maturity, a single first-lien senior secured tranche covering all term debt, a bilateral or small-club lender structure (typically 1-3 lenders), and a blended coupon reflecting the weighted-average economics of the combined layers. The structure simplifies the borrower's capital stack to a single credit agreement with a single security package.

Unitranche pricing in 2025 clusters in the SOFR+425-700 basis points range, with sponsored upper-middle-market deals at the lower end (SOFR+425-475) and weaker credits at the higher end (SOFR+550-700). The blended coupon is higher than pure senior debt would be (because it embeds compensation for the subordinated layer) but lower than what the borrower would pay across separate senior and mezzanine tranches.

Second-lien secured loans rank junior to first-lien debt on the same collateral pool, providing additional secured capacity beyond first-lien limits. They share a security interest in the same collateral as the first-lien debt but are subordinated in priority through an inter-creditor agreement defining the relative rights of the two lender groups in default and restructuring. Second-lien loans are typically held by a smaller institutional buyer base than first-lien (specialized credit funds, hedge funds, direct lenders rather than the broader CLO base).

Pricing runs meaningfully wider than first-lien, typically SOFR+750-1000 basis points in 2025, reflecting the structural subordination plus the narrower investor base. Second-lien tranches typically appear when sponsors stretch senior leverage beyond first-lien capacity, when a second-lien position is more efficient than a mezzanine layer, or in complex structures with multiple tranches optimized across different lender bases.

Mezzanine debt is structurally-subordinated quasi-equity that historically anchored sub-investment-grade financing alongside senior secured debt. The product has been partially displaced by unitranche but still appears in specific transactions.

Mezzanine Debt

A subordinated debt instrument that ranks below senior debt and above equity in the capital structure, typically featuring a cash coupon (8-12%) plus PIK (payment-in-kind) interest (2-4%) plus warrants or equity participation. Mezzanine debt is unsecured (or secured only by a junior pledge of equity in subsidiaries) and is structurally subordinated to senior secured debt. All-in expected returns range from 12-20%, comprising the cash coupon, the PIK accretion, and the equity participation upside. Mezzanine debt was historically a major leveraged finance product (especially in the 1990s and 2000s) but has been partially displaced by unitranche and second-lien products that offer borrowers tighter all-in pricing through simpler structures.

Structural Features

Mezzanine debt typically features a 7-10 year tenor (longer than senior secured), a structural subordination to all senior debt (with the subordination enforced through inter-creditor agreement and through the unsecured or junior-pledge security position), a combined cash plus PIK coupon structure where part of the interest accrues to principal rather than being paid in cash, and warrants or equity participation that provide the lender with potential equity upside on top of the debt return. The PIK component compounds principal each period:

Pricing Components

Mezzanine total return combines four pieces:

A typical structure: cash coupon (8-12% paid in cash), PIK accretion (2-4% accruing to principal rather than paid in cash), equity participation (2-8% from warrants or direct equity), and fees (1-3% from origination at closing). All-in expected return runs 12-20% depending on structure and credit profile.

The product set beyond TLB rounds out the leveraged finance toolkit and provides the structural building blocks for most complex capital structures. The next section of this guide moves to bond pricing, yield, and credit spreads, the technical foundation that DCM bankers use to price every transaction across the IG, HY, SSA, and loan markets covered in earlier sections.