How to Find Arbitrage Opportunities in Prediction Markets

Arbitrage — the ability to lock in risk-free profit by exploiting price differences across platforms — is one of the most reliable strategies in prediction market trading. This guide explains how to find and act on arbitrage opportunities systematically.

What is prediction market arbitrage?

Arbitrage occurs when the same event is priced differently on two or more platforms, and you can bet on all outcomes for a guaranteed profit regardless of the result.

Example: An event trades on two platforms:

• Platform A: "Yes" at 55¢ (implying 55%)
• Platform B: "No" at 40¢ (implying 40%)

The implied probabilities sum to 95% — less than 100%. You can buy "Yes" on Platform A for 55¢ and "No" on Platform B for 40¢, paying 95¢ total. One contract will pay $1, guaranteeing a 5¢ profit per pair regardless of outcome.

Why prediction markets have more arbs than traditional finance

Unlike stock markets with unified order books and high-frequency arbitrageurs, prediction markets are fragmented:

• Different platforms, different users — Kalshi attracts US political traders; Polymarket draws crypto-native global users
• No unified clearing — Each platform is its own silo with separate liquidity pools
• Slower price discovery — Lower trading volumes mean mispricings persist longer
• Regulatory barriers — US users can't access Polymarket; international users can't access Kalshi

These structural inefficiencies create persistent arbitrage opportunities that don't exist in more mature markets.

Step-by-step: Finding arbitrage

### 1. Identify overlapping markets

First, find events that trade on multiple platforms. Common overlapping categories:

• US elections — Kalshi, Polymarket, PredictIt
• Economic data (Fed rates, CPI, GDP) — Kalshi, Polymarket
• Sports outcomes — Polymarket, sportsbooks
• Crypto events — Polymarket, decentralized markets

### 2. Normalize the odds

Each platform uses different formats. Convert everything to implied probabilities:

from evsignals import markets
# Get cross-platform comparison
comparison = markets.compare("Fed rate decision March 2026")
print(comparison.implied_probabilities)

### 3. Check for arbitrage condition

Sum the cheapest "Yes" and "No" prices across platforms. If the sum is less than $1.00, an arbitrage exists.

from evsignals import scanner
# Find all active arbitrage opportunities
arbs = scanner.find_arbitrage(
    min_profit=0.02,  # At least 2% guaranteed profit
    platforms=["kalshi", "polymarket"]
)
arbs.head(10)

### 4. Account for fees and execution risk

Real arbitrage profits must exceed:

• Trading fees on both platforms
• Withdrawal fees (especially PredictIt's 5%)
• Slippage if the order book is thin
• Capital lock-up cost until settlement

A 5¢ theoretical arb might net only 2¢ after fees. EVSignals factors in platform-specific fee structures when calculating net arbitrage profit.

Automating arbitrage detection

Manual scanning is slow. The EVSignals +EV scanner runs continuously across 500+ sources and flags arbitrage opportunities in real time:

• Cross-platform price comparison updated every second
• Configurable minimum profit thresholds
• Fee-adjusted profit calculations
• Alert delivery via webhook, email, or dashboard

Risk management

Even "risk-free" arbitrage has practical risks:

• Settlement risk — Platforms may resolve the same event differently
• Execution risk — Prices may move between your two trades
• Counterparty risk — Platform solvency and withdrawal reliability
• Regulatory risk — Rules may change, especially for offshore platforms

Diversify across many small arbitrage positions rather than concentrating in one.

Getting started

1. Open accounts on multiple platforms (Kalshi for US, Polymarket for global) 2. Use EVSignals to scan for cross-platform arbitrage automatically 3. Start small — verify execution before scaling 4. Track your results in a notebook to refine your approach