Multi-Layer Capital Stacks
Real companies are rarely financed with a single class of capital. Instead, they build a stack, layers of debt and equity, each with its own priority, risk level, and required return. Understanding how these layers fit together is essential to understanding how value flows through a waterfall.
The Two Broad Categories of Capital
A company’s Total Invested Capital, also referred to as Business Enterprise Value when cash is removed or normalized, divides into two broad categories. Debt capital sits senior and is repaid first. Equity capital sits subordinate and participates in whatever value remains. Within each category, there is a spectrum of classes ranging from the most secure and lowest-returning at the top to the most subordinate and highest-returning at the bottom.
The Full Capital Spectrum
From least risk to most risk, the capital stack includes the following layers:
Asset Lending: Senior secured debt backed by specific assets. The most secure position with the lowest required return.
Cash Flow Debt: Unsecured debt repaid from company’s cash flow rather than asset collateral.
Mezzanine Debt: Debt with equity upside, often including warrants. It sits between senior debt and equity in priority and carries a higher return to compensate for the subordinate position.
SAFE: A Simple Agreement for Future Equity. It offers optionality, converting to equity at a future round, and sits senior to equity in a liquidation.
Preferred Equity: Equity with a preference. Preferred holds priority over common and carries negotiated rights around dividends, conversion, and participation.
Common Equity: The level of equity typically traded on public exchanges and the standard benchmark for incentives. Common participates only after all senior claims are satisfied.
Options: Any equity instrument contingent upon other instruments, such as warrants or profits interests. The most subordinate and highest-risk position in the stack.
Convertible Debt
Convertible debt is a promissory note used for bridge financing, pre-priced rounds, and structured downside protection. It is favored by private equity, crossover investors, family offices, and seed-focused funds.
Typical terms include mandatory repayment of principal plus interest, automatic conversion at a discounted price, and forced conversion at a valuation cap. Private equity investors frequently negotiate a cash repayment right for a stronger creditor position, along with board observer rights.
Liquidation Priority
Convertible debt is senior to equity and may be pari passu with or senior to other notes, depending on the intercreditor agreement. In some scenarios, a multiple of the invested amount is due, sometimes 1.5x to 2x, limited to non-qualified events. Protective provisions often include negative covenants on debt limits and asset sales, information rights, pro rata rights in the next round, and Most Favored Nation terms.
Conversion Terms
The conversion price is typically set at a 10 to 30 percent discount to the next round, with a valuation cap that limits upside on conversion. In a change of control or liquidity scenario, the holder can either take repayment of principal plus interest or convert and participate in the sale. Conversion is automatic in a qualified financing, a defined minimum raise, and optional at maturity, in a non-qualified financing, or in a change of control.
SAFE (Simple Agreement for Future Equity)
Created by Y Combinator in 2013 as a more founder-friendly alternative to convertible debt, a SAFE is not debt. It carries no maturity date and no interest. It is a contractual right to receive equity in a future round and is increasingly modified by institutional investors.
Core Economics
Cash is invested with no interest accrual and, in some cases, no repayment obligation. The SAFE remains outstanding until conversion or a liquidity event and holds priority over equity in a liquidation. SAFEs are typically pari passu with other SAFEs.
Conversion Mechanics
A SAFE automatically converts into equity issued in the next round. The conversion price is based on a discount of 10 to 30 percent, a valuation cap, or both. In a sale or liquidation, principal is repaid if funds are available, typically unsecured, and sometimes with a premium return, such as 1.5x.
How the Layers Interact
Each layer of the stack must be satisfied in order of priority before the next layer receives any value. Senior secured debt is repaid first, followed by unsecured and cash flow debt, then mezzanine, then SAFEs and convertible notes as they convert or are repaid, then preferred equity by round seniority, and finally common equity and options. The more layers in the stack, the more breakpoints exist in the waterfall, and the more complex the allocation of value becomes.
Structures Are Getting More Complicated
Real deals rarely resemble a clean stack. Multiple rounds of preferred, several convertible notes and SAFEs with different caps and discounts, option pools, and side letters all add layers and interactions. Each instrument creates new breakpoints and new participation rules. This complexity is precisely why a rigorous, forward-looking method like the Discounted Future Proceeds Method is necessary; simpler models cannot accurately allocate value across a truly multi-layered capital structure.
Why This Matters for the DFPM
Every layer in the capital stack carries its own risk and therefore its own required return. The Discounted Future Proceeds Method assigns each layer a discount rate that reflects its position in the stack, from approximately 12% for senior debt to 23.5% or more for options. By modeling each layer separately and discounting its expected proceeds at the appropriate rate, the DFPM connects the full capital structure back to the underlying business enterprise value.