Polymarket Copy-Trading Bot

A self-hosted bot that watches a curated set of profitable Polymarket wallets on-chain and replicates their positions in real time. It listens to the Polygon mempool and Polymarket's CLOB websocket, decodes order events, and re-sizes them against the operator's own bankroll and risk limits.

The hard part was not the copying — it was avoiding adverse selection. The bot models each followed trader's historical edge, decays stale signals, and refuses to chase fills that have already moved past a configurable slippage band. A circuit breaker halts trading on anomalous spread widening.

Profitable Polymarket traders move fast, and by the time a human notices a winning position the edge has usually evaporated. Naïvely copying them is worse than not trading at all: you inherit their adverse selection and pay the spread they already crossed.

I wanted to mirror a curated set of wallets automatically, but only when the trade still had positive expected value after slippage — and never in a way that could blow up the bankroll on a single anomalous fill.

I ingested signals from two sources for redundancy: the Polygon mempool for pending transactions and Polymarket's CLOB websocket for confirmed order events, deduplicating by order hash so a trade is never mirrored twice.

Each followed wallet carries a rolling model of its historical edge. Signals decay over time, and the execution engine refuses any fill that has already moved past a configurable slippage band. A circuit breaker halts all trading when spreads widen anomalously.

Position sizing is risk-scaled against the operator's own bankroll rather than copied 1:1, so a whale's $50k bet becomes a proportional fraction of available capital.