Optimal Execution among $N$ Traders with Transient Price Impact

Fuente: arXiv
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Main Authors: Campbell, Steven, Nutz, Marcel
Format: Preprint
Published: 2025
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_version_ 1866914570058072064
author Campbell, Steven
Nutz, Marcel
author_facet Campbell, Steven
Nutz, Marcel
contents We study $N$-player optimal execution games in an Obizhaeva--Wang model of transient price impact. When the game is regularized by an instantaneous cost on the trading rate, a unique equilibrium exists and we derive its closed form. Whereas without regularization, there is no equilibrium. We prove that existence is restored if (and only if) a very particular, time-dependent cost on block trades is added to the model. In that case, the equilibrium is particularly tractable. We show that this equilibrium is the limit of the regularized equilibria as the instantaneous cost parameter $\varepsilon$ tends to zero. Moreover, we explain the seemingly ad-hoc block cost as the limit of the equilibrium instantaneous costs. Notably, in contrast to the single-player problem, the optimal instantaneous costs do not vanish in the limit $\varepsilon\to0$. We use this tractable equilibrium to study the cost of liquidating in the presence of predators and the cost of anarchy. Our results also give a new interpretation to the erratic behaviors previously observed in discrete-time trading games with transient price impact.
format Preprint
id arxiv_https___arxiv_org_abs_2501_09638
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optimal Execution among $N$ Traders with Transient Price Impact
Campbell, Steven
Nutz, Marcel
Trading and Market Microstructure
Mathematical Finance
91A06, 91A15, 91G10
We study $N$-player optimal execution games in an Obizhaeva--Wang model of transient price impact. When the game is regularized by an instantaneous cost on the trading rate, a unique equilibrium exists and we derive its closed form. Whereas without regularization, there is no equilibrium. We prove that existence is restored if (and only if) a very particular, time-dependent cost on block trades is added to the model. In that case, the equilibrium is particularly tractable. We show that this equilibrium is the limit of the regularized equilibria as the instantaneous cost parameter $\varepsilon$ tends to zero. Moreover, we explain the seemingly ad-hoc block cost as the limit of the equilibrium instantaneous costs. Notably, in contrast to the single-player problem, the optimal instantaneous costs do not vanish in the limit $\varepsilon\to0$. We use this tractable equilibrium to study the cost of liquidating in the presence of predators and the cost of anarchy. Our results also give a new interpretation to the erratic behaviors previously observed in discrete-time trading games with transient price impact.
title Optimal Execution among $N$ Traders with Transient Price Impact
topic Trading and Market Microstructure
Mathematical Finance
91A06, 91A15, 91G10
url https://arxiv.org/abs/2501.09638