Arbitrage in Prediction Markets

The Inefficiency of Niche Markets

Prediction markets are still relatively inefficient compared to traditional finance. This creates massive opportunities for arbitrage—risk-free profit.

Strategy 1: Cross-Platform Arbitrage

Different platforms have different user bases.

• PredictIt restricts traders to $850 and charges high withdrawal fees. It often skews conservative.
• Polymarket is global, crypto-native, and uncapped.

Example:

• Event: "Will Inflation exceed 4%?"
• PredictIt Price (Yes): 65¢
• Polymarket Price (No): 40¢

You can buy Yes on PredictIt and No on Polymarket.
Total Cost: $0.65 + $0.40 = $1.05. (This is a loss, bad trade).

Arbitrage Opportunity:

• PredictIt (Yes): 55¢
• Polymarket (No): 40¢
  Total Cost: $0.95.
  Regardless of the outcome, one side pays $1.00. You make a guaranteed $0.05 profit (5% ROI instantly).

Strategy 2: Negative Risk (Dutch Book)

In a categorical market with 3 mutually exclusive outcomes (A, B, C), the probabilities should sum to 100% ($1.00).
However, due to liquidity crunches or panic selling, the prices might sum to less than $1.00.

Scenario:

• Outcome A: $0.30
• Outcome B: $0.30
• Outcome C: $0.30
• Sum: $0.90

Action: You buy "Yes" on A, B, and C.
Cost: $0.90.
Payout: One of them MUST win (paying $1.00). The others go to $0.
Profit: $0.10 risk-free.

This is common in sports markets or elections with many candidates where liquidity is thin on the long-tail candidates.