M Wright and MP Wellman

17th International Conference on Autonomous Agents and Multiagent Systems, pages 614–622, July 2018.


The continuous double auction (CDA) is the predominant mechanism in modern securities markets. Many agent-based analyses of CDA environments rely on simple non-adaptive trading strategies like Zero Intelligence (ZI), which (as their name suggests) are quite limited. We examine the viability of this reliance through empirical game-theoretic analysis in a plausible market environment. Specifically, we evaluate the strategic stability of equilibria defined over a small set  of ZI traders with respect to strategies found by reinforcement learning (RL) applied over a much larger policy space. RL can indeed find beneficial deviations from equilibria of ZI traders, by conditioning on signals of the likelihood a trade will execute or the favorability of the current bid and ask. Nevertheless, the surplus earned by well-calibrated ZI policies is empirically observed to be nearly as great as what the adaptive strategies can earn, despite their much more expressive policy space. Our findings generally support the use of equilibrated ZI traders in CDA studies.