Yuki Nakamura extends privacy-subsidy model to continuous-time Kyle AMMs
Closed-form formula links privacy noise to LVR, quantifying break-even fees for AMMs.
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Yuki Nakamura has released a new paper that extends the closed-form privacy-subsidy result from a single-period Kyle model to a continuous-time setting. The work models a committed Bayesian automated market maker (AMM) that observes aggregate order flow perturbed by an independent Brownian privacy channel of diffusion intensity σ_ε. In the Markovian linear equilibrium, the price-impact coefficient λ becomes constant over time, expressed as λ = σ_v / √(σ_u² + σ_ε²). This leads to a closed-form cumulative expected transfer from the protocol's liquidity pool to traders over the interval [0,1]: |Π_M| = σ_v σ_ε² / √(σ_u² + σ_ε²).
Crucially, the paper establishes a structural duality between this cumulative privacy subsidy and the Loss-Versus-Rebalancing (LVR) measure introduced by Milionis et al. (2022). Nakamura identifies privacy-noise welfare as the order-flow observation analog of LVR's price-observation gap. The result completes a program to quantify break-even fees for committed-AMM exchanges operating under privacy-aggregated information environments. The paper is the third in a cluster of works by Nakamura (companions: arXiv:2605.15746, arXiv:2605.19742) and runs 13 pages, contributing to computer science and game theory, cryptography, probability, and trading microstructure.
- Extends single-period Kyle privacy-subsidy result to continuous-time with closed-form cumulative transfers
- Constant price-impact coefficient λ = σ_v / √(σ_u² + σ_ε²) derived for Markovian linear equilibrium
- Establishes structural duality between privacy subsidy and Loss-Versus-Rebalancing (LVR) from Milionis et al. 2022
Why It Matters
Provides a theoretical foundation for designing fee structures in privacy-preserving AMMs, connecting privacy noise to market efficiency.