Profit from Polymarket Pricing Errors — Automatically.
Arbitrage on Polymarket is the closest thing to a risk-free trade in prediction markets. It exploits a mathematical constraint baked into every binary market. Understanding how it works — and why execution speed is everything — is the foundation of automated trading on Polymarket.
Strategy
How Polymarket Arbitrage Works
Polymarket is a binary prediction market — every event resolves to exactly YES ($1.00) or NO ($1.00). Arbitrage emerges when pricing deviates from this mathematical certainty.
Direct Spread Arbitrage
When YES + NO < $1.00
The most straightforward form. When the sum of YES and NO shares in a single market drops below $1.00, buying both sides guarantees a profit at resolution. For example, if YES trades at $0.48 and NO at $0.47, you spend $0.95 to guarantee $1.00 — a risk-free 5.3% return, regardless of the event outcome.
Buy YES @ $0.48 + Buy NO @ $0.47 = $0.95 cost. Guaranteed $1.00 payout at resolution. Net: $0.05 profit per share pair.
Cross-Market Correlation
Logical Inconsistencies Across Markets
Related markets sometimes price events inconsistently. For example, a specific candidate winning an election should always have a price at or below the broader category outcome. If it doesn't, a logical violation exists. Polysized maintains a graph of market relationships and continuously checks for violations.
Candidate market at 55% while the broader category markets at 48%. Logically impossible — if the candidate wins, the broad category wins. Enter both positions before the market corrects.
Time-Decay Arbitrage
Near-Resolution Markets
As markets approach resolution, prices should converge toward 0% or 100%. Markets that lag behind a real-world outcome create directional opportunities. Polysized monitors live news feeds with AI to detect when a market price has not yet reflected a breaking development.
Breaking confirmation published. Market still at 72%. AI model signals 98% probability of resolution. Buy at 72% before the market reprices — directional trade, not pure arbitrage.
Execution
Why Speed Is the Entire Edge
Arbitrage opportunities on Polymarket typically exist for 2 to 15 seconds before other traders or automated systems correct the pricing error. By the time you spot an opportunity, open both order forms, and execute manually, the spread has already closed.
Polysized solves this with a high-frequency pipeline that monitors order book depth via WebSockets, detects pricing violations in real-time, and routes orders through dedicated Polygon RPC nodes for sub-100ms execution. Smart rate limiting keeps the bot within Polymarket's API limits while maximising fill rates.
Combined with Kelly Criterion position sizing and automated trailing stop-losses, Polysized manages the entire trade lifecycle — from detection to execution to exit — without any manual intervention.
Risk Management
Safety Even in Risk-Free Trades
Even with arbitrage, risk management matters. Polysized applies institutional-grade controls on every position.
Non-Custodial
EIP-7702 smart wallet delegation lets you grant access only to your allocated trading amount. Polysized cannot withdraw or move more than your authorised funds.
Kelly Criterion Sizing
Every arbitrage position is sized optimally — large enough to be profitable against transaction costs, small enough to protect against edge cases and partial fills.