A Derivative Pricing Perspective on Liquidity Tokens in Constant Product Market Makers
Maxim Bichuch, Zachary Feinstein
TL;DR
The paper addresses mispricing and hedging of liquidity tokens in constant product market makers (CPMMs) by reframing LP positions as derivative claims on underlying pool assets and developing a risk-neutral valuation framework. It derives a Bermudan-style pricing problem with a critical fee-threshold $\hat{\gamma}^*$, yielding a closed-form price $V_0(P_0)$ when $\hat{\gamma} \ge \hat{\gamma}^*$ and a corresponding set of Greeks for hedging. The authors further define implied volatility notions $\sigma^I$ and propose data-driven calibration $\sigma^M$ to obtain arbitrage-free prices, demonstrated on Uniswap-like data and showing reduced hedging error under re-pricing. Finally, they propose two novel AMM designs with liquidity-dependent minting/burning costs and fee rates to allow fully dynamic, arbitrage-free pricing of liquidity tokens, with implications for DeFi risk management and AMM design. Overall, the work provides a rigorous financial-derivatives framing for CPMMs, offers practical calibration methods, and suggests design directions to stabilize liquidity markets in DeFi.
Abstract
In decentralized finance, any individual can pool their assets into an automated market maker (AMM) -- herein we focus on the constant product market maker (CPMM) -- in exchange for a claim on a fraction of future pool assets and fees earned from the market making operations. This position is represented by a liquidity token, whose prevailing on-chain price is effectively the initial deposited assets. Though this price is well-defined, we treat the liquidity token as a derivative position in the prices of the underlying assets for the CPMM in order to deduce risk-neutral pricing and hedging formulas, not dissimilar to the Black-Scholes result. Adopting this perspective, in a frictionless environment, hedging the CPMM liquidity token under fair valuation should produce a riskless process, which therefore grows at the risk-free rate, something that is not seen in empirical case studies under the prevailing price. With our novel pricing formula, we construct a method to calibrate a volatility to data which provides an updated (non-market) valuation which is consistent with the (near-continuous) replication strategy out-of-sample. We conclude with a discussion of novel AMM design considerations motivated by this derivative-pricing perspective.
