Polymarket Arbitrage Strategies

Cross-platform Arbitrage: This involves finding differing odds for the same event across Polymarket and traditional sportsbooks or other prediction markets like Kalshi. Users report using bots to "de-vig" sportsbook odds to determine fair value, then placing limit orders on Polymarket with a profitable edge. "Polymarket's price just lagged the sportsbooks. So I'd de-vig the bookie odds to get a fair value, place limit orders with a >7% edge on Polymarket, then if any of those orders got filled I'd hedge the other outcome to lock the arb."

Single-Winner Market Arbitrage: In markets where only one outcome can win (e.g., "Who will be US President?"), Users have attempted to buy "NO" contracts on multiple candidates. The principle is that if you buy "NO" on all losing candidates, you are guaranteed a payout from the winner. "Du kaufst NO auf A + NO auf B = 85¢ Gesamtkosten. Egal wer gewinnt: Du bekommst 100¢ → 15¢ Gewinn = 17.6% ROI."

"Boring" Niche Arbitrage: Some Users have found success by focusing on niche markets with less competition, such as esports or specific weather events, where wider spreads and less efficient pricing can be found. "His entire edge was in esports markets (specifically CS2, Dota, and LoL) where he found massive 20 to 30¢ spreads that nobody else was pricing."

Slippage and Liquidity: Limited liquidity in Polymarket's order book can make it difficult to execute large arbitrage trades at desired prices, leading to slippage. "Slippage: Das Orderbuch hat nicht immer genug Liquidität."

Execution Speed and Competition: The market for arbitrage is highly competitive, with faster bots and institutional players often capturing opportunities before retail traders. "You're now competing against established companies with almost infinite pockets and math PhDs."

Unhedged Positions: When one leg of an arbitrage trade fills but the other doesn't, traders can be left with a "naked" or directional bet, which carries risk. "The thing with Polymarket is that you can't capture these arbs cleanly. You post limit orders on both teams and wait, and one leg always fills before the other - so you stop quoting that team and try to get the hedge filled on the other side."

Automated Bots: Many Users develop or utilize automated bots (often written in Python) to scan for and execute arbitrage opportunities across various platforms. "I built the entire arbitrage trading bot using AI."

Arbitrage Scanners: Tools and websites exist that scan for arbitrage opportunities between Polymarket and other platforms like Kalshi, though liquidity can still be an issue. "I created a Polymarket x Kalshi Arbitrage Finder. It can automatically scan all the markets across these platforms to find arbitrage betting opportunities."