Middle market acquisition financing breaks most often not at the senior debt level but at the intersection between the senior facility and the subordinated capital below it. Senior lenders will underwrite against a defined EBITDA multiple and DSCR threshold. Everything below the senior lender's ceiling must be structured to produce covenant compliance at every quarterly test date without senior lender amendment.
Senior lenders in middle market acquisitions apply specific underwriting calculations that define the debt ceiling before any subordinated capital is considered. The calculations are documented in the term sheet and the credit agreement, and they operate consistently across the middle market lending universe.
The specific tests:
The senior lender's underwriting is calculation-driven, not judgment-driven. The acquirer who runs these calculations at LOI stage knows the debt ceiling before commencing negotiations. The acquirer who does not run the calculations discovers the ceiling when the senior lender's term sheet arrives.
Mezzanine debt and unitranche occupy the space between senior debt and equity. The two instruments serve similar purposes but operate through different structures with materially different implications for acquirer flexibility.
Traditional mezzanine debt sits below senior debt in the capital stack. It carries cash interest of 12-16 percent plus PIK of 2-4 percent plus warrants or equity co-investment rights. The mezzanine lender and senior lender negotiate an intercreditor agreement that governs payment priority, standstill provisions, and workout mechanics. The all-in cost including warrants typically reaches 18-22 percent.
Unitranche debt combines senior and subordinated components into a single facility from a single lender. The lender may sell first-out or last-out positions to other lenders through an agreement among lenders, but the borrower sees one facility with one set of covenants. All-in cost typically runs 10-13 percent, effectively bridging the gap between senior debt (7-9 percent) and traditional mezzanine (18-22 percent all-in).
| Instrument | Size (% Of EV) | Interest Rate Range | Amortization | Subordination | Covenant Implications |
|---|---|---|---|---|---|
| Senior Term Loan | 45-55% | SOFR+300-450bps | 5-7 year | None | Full covenant package |
| Senior Revolver | 5-10% | SOFR+275-400bps | Bullet | None | Same as term |
| Unitranche | 55-65% (combined) | SOFR+500-700bps | 5-7 year | AAL first-out/last-out | Single covenant set |
| Mezzanine Debt | 10-15% | 12-16% cash + 2-4% PIK | 7-8 year bullet | Contractual payment sub | Springing covenants |
| Seller Note | 10-15% | 8-12% | 5-7 year | Full payment sub | None typically |
| Preferred Equity | 5-15% | 12-16% div + participation | Perpetual | Below all debt | None typically |
| Common Equity | 30-40% | Residual returns | None | Last | None |
Seller note interaction with the senior facility produces post-close complications when the subordination structure is not properly designed. Senior lenders require specific provisions to protect their credit position, and sellers frequently underestimate what senior lenders will accept.
The specific senior lender requirements in seller note subordination:
The interaction that produces post-close complications: seller notes with insufficient subordination trigger senior lender concerns that surface at each amendment request or covenant issue. Senior lenders who view the seller note as inadequately subordinated impose additional restrictions or higher pricing on future amendments.
Blended cost of capital analysis reveals the actual economic cost of the capital stack, which frequently differs from what individual instrument pricing suggests.
Consider an illustrative $300M acquisition financed with:
Total debt service: $22.8M cash + $4M PIK = $26.8M all-in on $210M of debt = 12.8 percent blended cost.
Alternative structure with unitranche:
Total debt service: $20.4M cash + $2.5M PIK = $22.9M on $210M of debt = 10.9 percent blended cost.
The blended cost analysis reveals that unitranche produces $3.9M in annual debt service savings versus the senior plus mezzanine structure. Over a 5-year hold, the savings compound to $19.5M in additional free cash flow available for debt reduction or return to equity.
The blended cost is not the only decision variable. Unitranche typically carries prepayment premiums that traditional senior debt does not. Mezzanine warrants transfer equity value to the mezzanine lender that unitranche does not. But the blended cost analysis provides the starting point for evaluating whether the capital structure is optimally designed.
Three failure patterns produce most middle market financing structure breaks in year one.
Pattern 1: DSCR compression from cash pay subordinated debt. The acquirer models mezzanine or seller note at PIK, then the term sheet arrives with cash pay requirements. The compressed DSCR breaches at the first quarterly test. Remediation requires either covenant amendment (with pricing step-up) or PIK conversion (with structural cost).
Pattern 2: EBITDA underperformance in the first 6 months. The acquirer's pro forma EBITDA assumes synergies or growth that has not materialized by month six. The senior lender's covenant EBITDA falls below the covenant threshold. Remediation requires covenant waiver (with fees) or acceleration of synergy realization (with integration cost).
Pattern 3: Working capital expansion beyond peg. The acquirer's structure assumes working capital normalized at the peg level. Post-close working capital expands 15-25 percent above the peg, consuming cash that should service debt. The revolver draws increase, and total leverage rises above the leverage covenant. Remediation requires covenant amendment or working capital compression.
Each pattern is preventable through disciplined pre-close LBO model stress testing analysis. Each pattern is common when the analysis is deferred.
Acquisition financing structure operates within Layer 4 of the Buy-Side Advisory five-layer architecture during deal underwriting and decision support. The Capital Readiness Scorecard governs how the capital structure is read against the target's free cash flow.
Middle market acquisition financing succeeds or fails on the senior lender's underwriting calculations. Institutional discipline applied to the senior facility structure, the subordination mechanics below it, and the blended cost analysis across the full stack produces structures that survive year one. Absent that discipline, the covenant amendment arrives at month twelve.
Institutional underwriting modeling and structuring support for buy-side acquirers.
How to structure seller notes to align with senior debt covenants and protect buyer equity.
How institutional downside scenarios apply multiple simultaneous stresses and test covenant compliance.
The institutional method for calculating Debt Service Coverage Ratio in middle market acquisitions.
The diagnostic tool identifying gaps in acquisition underwriting and structuring defensibility.
The framework governing how capital structure is read against the target's free cash flow.