Test-Time Communication in Trading Agent Swarms

The paper investigates how communication affects trading agents that operate independently rather than as a coordinated team. Over seven trading days, 200 agents from four model families were grouped under five communication regimes, from isolation to shared message boards, and their reading logs were recorded before each decision. Results showed that in two model families, communicating groups held more of the same stocks than isolated groups, and a group’s return was largely driven by shared holdings; agents were more likely to reuse phrases from groupmates, and communicating groups tended to sell in step more often than isolated ones, though isolated groups also converged on similar stocks, indicating that herding assessments must compare against a no‑peer baseline.