Prediction Market Arbitrage: Hidden Costs, Fees, and the Real Math
The idea sounds beautiful: buy "Yes" on one platform for $0.40, buy "No" on another for $0.55, and collect $1.00 for a total outlay of $0.95. Five percent risk-free.
In practice, three layers of costs, several non-obvious risks, and different resolution rules across platforms stand between you and those 5%.
Three Layers of Costs
1. Platform Trading Fees
The key trap: many DEX platforms use dynamic fees that depend on event probability.
| Platform | Taker Fee | Maker Fee | Payout Fee | Notes |
|---|---|---|---|---|
| Polymarket | 0–1.8% (peaks at 50/50) | 0% + rebate | 0% | Geopolitics markets: 0% |
| Limitless | 0.03–3% | 0–1.5% | — | Lower fee for likelier outcomes |
| Predict.fun | 1–2% (standard) | — | — | Often zero-fee promos + cashback |
| Opinion | 1–2% | — | — | Fee goes to LP pool |
| Kalshi | Fixed | — | — | Regulated exchange, USD, not Web3. US residents only |
2. Network Gas Fees
| Network | Platforms | Gas per TX | Native Token |
|---|---|---|---|
| Polygon | Polymarket | Fractions of a cent | MATIC / POL |
| Base | Limitless, Opinion | $0.01–0.05 | ETH |
| BNB Chain | Predict.fun | $0.03–0.10 | BNB |
3. Cross-Chain Bridges
Bridge fees: $1–5 per transfer + percentage. Time: 1–15 minutes (spread may close while you wait).
Three Critical Risks
1. Slippage
AMM worsens your price on large orders due to thin liquidity.
2. Resolution Risk — Where 90% of Arbitrageurs Burn
Same event, different platforms, different resolution rules and data sources. Your positions can lose on both sides simultaneously.
3. Timing Lag
No atomic cross-chain execution. Second leg may execute after the spread closes.
Minimum Spread for Break-Even
| Cost Item | Approximate |
|---|---|
| Platform A fee (taker) | 1.0–1.8% |
| Platform B fee (taker) | 1.0–2.0% |
| Gas (4–6 transactions) | $0.10–0.50 |
| Slippage (both legs) | 0.5–2.0% |
| Total | 3–6% |
Profitable arbitrage realistically starts at 7–10% spreads.
Premarket.me — Aggregator for Arbitrage
Manually monitoring spreads across five platforms is impractical. Premarket.me solves this: it's a prediction market aggregator with a unified API that combines data from Polymarket, Limitless, Predict.fun and other platforms.
The key endpoint — /api/arbitrage — returns pre-calculated pairs: where to buy "Yes", where to buy "No", total cost, profit %, APR adjusted for time to expiry, and liquidity depth in USD.
Open-Source Arbitrage Bot
A ready-made Go arbitrage bot built on the Premarket API: suenot/premarket-arbitrage-bot.
Scanner (Premarket API) → Filter (profit/APR/depth) → Display → Executor (Polymarket CLOB)
The bot polls /api/arbitrage, filters pairs by configurable thresholds (MIN_PROFIT_PCT, MIN_APR, MIN_DEPTH_USD), and optionally executes trades via Polymarket CLOB with EIP-712 signing. Default mode: DRY_RUN=true (monitoring only).
Links
- 🌐 Polymarket · Limitless · Predict.fun · Opinion · Kalshi
- 🌐 Premarket.me: premarket.me · API Docs
- 💻 Arbitrage Bot: suenot/premarket-arbitrage-bot
Conclusion
Prediction market arbitrage is not "free money." It's systematic work with three layers of costs, cross-chain logistics, and resolution risk that can wipe out both legs of a trade. Minimum spread for break-even is 5%; for profit — 7–10%.
But the key insight: mechanical arbitrage alone is not enough. The real edge comes from building AI agent analytics around each specific bet: real-time news monitoring, tracking social signals, analyzing on-chain activity of large players, and correlating with macro events. The spread between platforms is a symptom; the cause is information asymmetry. The winner is the one who understands that event probability has shifted — not the one who clicks the button fastest.
Pre-funding wallets, maker orders, and API automation are table stakes. The real edge is in the analytical layer on top of market data.
MarketMaker.cc Team
Quantitative Research & Strategy
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