Above the Waterfall: Mezzanine and HoldCo Financing for Infrastructure Fund stacks

Infrastructure debt has long been considered one of the most dependable corners of private credit: long-dated, asset-backed, underpinned by essential services and contractual cash flows. That reputation is well-founded, but it belongs primarily to one part of the capital stack. The senior project finance debt piece, lent directly at SPV or operating company level, is the product that built that reputation. The market that has grown rapidly around it, mezzanine and HoldCo financing at fund level, is a structurally different proposition, with a different risk profile, a different lender base, and an operational complexity that demands a different quality of administration.

This article examines that distinction: where mezzanine and HoldCo financing sits in the infrastructure capital stack, why it exists, who provides it, and what the structural and operational demands of these facilities actually require.

The Infrastructure Capital Stack: Where Mezzanine Sits

To understand mezzanine and HoldCo financing in infrastructure, the starting point is the waterfall.

Senior project finance debt is structured at the SPV or operating company level, secured directly against the project’s physical assets and contractual cash flows. Structured cash flow waterfalls dictate revenue allocation, ensuring that maintenance reserves, debt service and capital expenditures are covered before any excess cash is distributed upward. Debt Service Coverage Ratio covenants are the primary credit control mechanism: if cash flow falls below a defined threshold, distributions to equity are locked up, and in more severe scenarios, cash sweep provisions accelerate repayment. Before financial close, the DSCR drives the size and shape of the loan through debt sizing and sculpting; after financial close, it determines whether equity distributions are restricted or whether lenders can exercise default remedies.

Mezzanine and HoldCo financings sit above all of this. HoldCo financing is structurally subordinated: lenders at the HoldCo level do not have direct security over project assets and must rely on the residual cash flows that remain after the project has met all its senior debt obligations, operational expenses and reserve requirements. In practical terms, HoldCo lenders are last in the queue for cash. The mezzanine is not a “mezz” in the traditional corporate finance sense, with a Junior tranche and Senior that are contractually linked in a documentation. In this infrastructure concept, the HoldCo financing is structurally a mezzanine financing, with its cash flow subordination in the waterfall.

This structural subordination is not a defect. It is the defining feature of the product, and it is priced accordingly.

Why HoldCo Financing Exists and Who Uses It

Infrastructure funds use HoldCo and mezzanine facilities for a range of purposes: bridging the gap between equity deployment and project-level debt, funding portfolio construction, supporting add-on acquisitions, and managing liquidity at the fund level without disturbing the project financing below. HoldCo financing is used and discussed in a variety of contexts, encompassing portfolio financings and warehouse structures as mechanisms to deploy capital at scale, with pre-set standards for eligible projects and the ability to diversify once a critical mass of operational assets is reached.

PIK facilities are common at the HoldCo level, offering borrowers the option to pay interest in cash or capitalise it, with cash preservation being a key structural attraction. This reflects the cash-flow-remote nature of the position: where DSCR covenants at the project level restrict dividend flows upward, a PIK mechanism at the HoldCo level allows the structure to function without placing immediate cash pressure on a borrower whose access to liquidity depends on what the project allows to pass through. PIK financing at the holding company level can also provide incremental capital for bolt-on acquisitions without straining the senior debt package, and as exit timelines lengthen, PIK instruments bridge capital needs for growth or liquidity management.

Recent examples illustrate the scale and ambition of this market: in January 2026, DC BLOX secured a $240 million HoldCo financing facility from Global Infrastructure Partners, providing growth capital for a hyperscale data centre expansion strategy. HoldCo facilities are no longer boutique instruments reserved for the most sophisticated sponsors. They are becoming a standard feature of infrastructure fund finance.

The Risk Profile: Why Banks Step Back and Private Credit Steps In

The contrast with senior project finance could not be sharper. Senior infrastructure debt benefits from direct asset security, tight DSCR covenants, Debt Service Reserve Accounts or Cash Trap mechanics, and a track record of low default and recovery rates that commercial banks understand well. Historically, banks provided over 90% of infrastructure project debt before 2008, but in 2025, institutional investors and private debt platforms had become a core part of the infrastructure financing ecosystem, competing alongside traditional banks across the capital stack.

Not all private credit funds in infrastructure take the risk level found higher in the capital structure, and direct lending deals do exist at project level. But credit funds tend to look for higher yield than traditional banks which shifts some towards different territories. For lenders, the absence of direct recourse and asset-level security at the HoldCo level translates into a higher risk profile and commands higher returns compared with senior project-level debt. Private high-yield BB infrastructure credit spreads in 2025 have typically started in the high 200s to low 300s basis points over SOFR, for a yield of approximately 7% or higher, reflecting investors’ need to be compensated for illiquidity and single-asset risk. At the mezzanine and HoldCo level, returns are higher still, targeting above double-digit returns to compensate for the subordinated, cash-flow-remote position.

This is not territory for bank balance sheets operating under capital adequacy constraints. The private credit market now extends beyond senior loans to include junior lending with equity upside, mezzanine financing, infrastructure debt and asset-backed finance, with tailored solutions that traditional bank lenders historically would not provide. Infrastructure debt funds, specialist mezzanine managers and private credit platforms have stepped into these positions precisely because they can price, structure and hold the risk that banks cannot.

In 2025 alone, close to $300 billion were raised across closed-end infrastructure funds, with private debt capital supporting the deployment of that equity into both greenfield and brownfield projects. The market is large, growing rapidly, and increasingly reliant on non-bank lenders across the full capital stack.

Structural Complexity and the Intercreditor Challenge

At its core, the operational challenge for mezzanine and HoldCo infrastructure financing is around the intercreditor.

Senior project lenders and HoldCo lenders are financing different parts of the same structure, with fundamentally different security packages, different enforcement rights, and potentially conflicting interests when a project comes under stress. To mitigate these risks, HoldCo loans typically include tighter covenants, cash sweeps, dividend traps, and intercreditor agreements that limit distributions from the SPV if financial conditions deteriorate. Negotiating and administering those agreements requires an agent that understands both layers of the structure, not just the facility it is directly administering.

Because HoldCo lenders typically rely more heavily on governance rights and structural controls than asset-level security, monitoring information flows and consent mechanics becomes central to protecting lender value. In these structures, the quality of reporting, covenant monitoring and decision execution becomes part of the credit protection itself.

PIK mechanics at the HoldCo level introduce a further layer. Where cash interest is being toggled to PIK (either because dividend flows from the project are restricted by DSCR lock-ups or because the sponsor has elected to capitalise) the agent must track accruing obligations, manage capitalisation mechanics correctly, and ensure that the growing principal balance is reflected accurately across all lender positions. Errors here do not correct themselves: they compound.

The security package for HoldCo instruments is typically limited to shares in the borrower and its bank accounts, with enforcement by creditors structured either above or below the HoldCo borrower depending on the documentation. In cross-border structures, which are the norm in European infrastructure, where assets span multiple jurisdictions and holding structures may involve Luxembourg, Netherlands, or other intermediate holding companies, the security agent must coordinate enforcement mechanics across legal systems simultaneously. International senior, sub-senior and mezzanine lenders are increasingly active in European energy infrastructure, and structures now contain financing features that were typically seen only in project finance, acquisition finance or asset finance respectively, often within the same transaction.

Jumbo HoldCo financings have also emerged, with private credit funds forming clubs to provide financings in excess of £1 billion in some cases, pooling resources and sharing risk. A syndicated HoldCo facility of that scale, across multiple lenders, multiple jurisdictions and a complex intercreditor architecture, is not a structure that administers itself.

Getting the Basics Right

At the HoldCo and mezzanine level, the agent must understand how DSCR thresholds trigger dividend lock-ups, how PIK elections interact with capitalisation mechanics, and how intercreditor agreements govern enforcement sequencing. An agent that does not understand these dynamics is not a neutral function. It is a structural risk.

In practice, these transactions are less operationally complex than the senior infrastructure deals that command most of the market’s attention. What they require is not heroics: it is precision, consistency, and an agent who has read the intercreditor agreement and knows what it says.

That is a surprisingly narrow field.

Clément Couloumy, Senior Director