Accreting Swap
An accreting swap is an interest rate or currency swap in which the notional principal increases over the life of the contract according to a predetermined schedule, making it the structural inverse of an amortizing swap and a natural hedging instrument for borrowers whose debt draws down progressively over time. The accreting structure aligns the swap's notional exposure with the growing outstanding balance of the underlying obligation.
Key takeaways
- The notional principal grows on a fixed schedule, meaning interest payment obligations increase over time on both legs of the swap.
- Accreting swaps are most commonly used by project finance borrowers, construction loan recipients, and mortgage originators whose loan balances build up during a drawdown phase.
- Pricing an accreting swap requires discounting cash flows at each notional step, with the fixed rate set so the present value of fixed payments equals the present value of floating payments at inception.
- Credit exposure (potential future exposure) in an accreting swap is front-loaded because the notional grows, increasing counterparty risk as the deal ages—the opposite of an amortizing swap.
- Under ISDA documentation, accreting swaps can be structured as a series of vanilla swaps with staggered effective dates, simplifying confirmation and netting calculations.
Explanation
In a standard fixed-for-floating interest rate swap, both parties reference a constant notional principal that never actually changes hands—it merely serves as the base for computing periodic cash flows. In an accreting swap, this notional amount increases at specified intervals or according to a formula tied to an underlying loan drawdown schedule, capital call schedule, or index. The economic rationale is straightforward: if a borrower has a construction loan that funds $20 million per quarter over two years, paying fixed rate on a $160 million notional from day one would create an overhedral overhedge for the initial period. An accreting swap that starts at $20 million and grows by $20 million per quarter matches the hedge to the actual exposure.
Pricing an accreting swap proceeds by bootstrapping the relevant swap curve (SOFR-OIS in USD post-LIBOR transition) and computing the present value of floating cash flows at each notional increment. The fixed rate is then solved iteratively such that the net present value of the swap is zero at inception—standard no-arbitrage swap pricing, but applied to a vector of notionals rather than a scalar. The result is typically a fixed rate slightly different from the vanilla par swap rate for the same maturity, since the notional profile weights the payment dates differently.
Credit risk management in accreting swaps demands particular attention. In a standard swap, potential future exposure (PFE) peaks in the middle of the deal's life as both the notional and time remain significant. In an accreting swap, PFE is skewed toward the end of the deal because the notional is largest in later periods. This affects internal capital allocation for counterparty credit risk and can influence the credit support annex (CSA) thresholds and initial margin requirements under UMR (Uncleared Margin Rules) for bilateral OTC trades.
From a structured finance perspective, accreting swaps appear in CLO warehouses, where a manager accumulates a portfolio of loans before the deal prices; the swap notional accretes in line with the warehouse facility drawdown. They also feature in infrastructure project finance deals, where construction-period debt grows to full utilization before operations begin and cash flow sweeps start. In both cases, the accreting structure prevents the cost of over-hedging while maintaining continuous interest rate or currency protection.
Formula
Fixed Rate set so: Σ [Fixed Rate × Notional(t) × day_count(t) × DF(t)] = Σ [Forward Rate(t) × Notional(t) × day_count(t) × DF(t)]
Example
A renewable energy developer is constructing a wind farm financed by a $300 million construction loan that draws $50 million every six months for three years. To hedge the variable-rate loan (SOFR + 200 bps), the developer enters an accreting interest rate swap where the notional increases by $50 million every six months: $50M in months 1-6, $100M in months 7-12, through to $300M at maturity. The fixed rate is set at 5.25% (vs. SOFR flat) at inception. If SOFR rises to 5.50% by the third drawdown, the developer pays 5.25% fixed and receives 5.50% floating on the $150M then-current notional, netting $375,000 semiannually on that tranche—an economically meaningful offset to the higher debt service cost.
Related terms
American Option Arbitrage Capital Call Credit Risk Credit Support Annex Currency Swap Drawdown Final Settlement Price Futures Price Hedging Initial Margin Interest Rate