How to Spot Insider Trading Patterns on Polymarket

Introduction

Polymarket, a decentralized prediction market platform, has come under scrutiny for potential insider betting, particularly on military and defense actions. Research by the Anti-Corruption Data Collective reveals that long-shot bets—wagers of $2,500 or more at odds of 35% or less—in these niche markets boast an average win rate of approximately 52%, far surpassing the 25% win rate across all political markets and the 14% overall platform average. This stark discrepancy suggests informed participants may be leveraging non-public information to place winning bets. While insider betting on Polymarket remains legal, its impact on political and military markets could distort outcomes and erode trust. This guide will walk you through a systematic approach to identifying such anomalies using publicly available data.

What You Need

• Access to Polymarket: Create an account or use public data APIs to view market activity.
• Data collection tool: A spreadsheet application (e.g., Excel, Google Sheets) or Python with libraries like pandas for analysis.
• Basic understanding of odds and betting concepts: Know how to interpret implied probability from odds (e.g., odds of 35% mean a $100 bet pays ~$285 if correct).
• Historical market data: For the most accurate analysis, export trade history from specific markets, especially those related to military or defense actions.
• Time and patience: Repeat the method across multiple markets to spot consistent patterns.

Step-by-Step Guide

Step 1: Identify High-Risk Markets

Begin by focusing on markets with the highest potential for insider knowledge. The Anti-Corruption Data Collective’s analysis indicates that military and defense actions are particularly prone to abnormal win rates. On Polymarket, navigate to the “Military & Defense” category. Look for markets where the outcome is tied to non-public intelligence, such as troop movements, weapons tests, or geopolitical events. Avoid broad markets (e.g., election winners) as they are less likely to exhibit insider patterns.

Step 2: Filter for Large, Long-Shot Wagers

Insider bets often hide in plain sight as long-shot wagers. Use the platform’s trade history or an API to extract all trades meeting these criteria:

• Bet size ≥ $2,500 (single transaction or cumulative from one wallet).
• Implied odds ≤ 35% (i.e., the price to buy a share is $0.35 or less per share).

These parameters isolate bets that are risky by nature but become suspicious when they succeed consistently. For example, a $2,500 bet on a 30% probability event might seem like a punt—unless it wins frequently.

Step 3: Calculate the Win Rate for Those Bets

For each filtered bet, track whether the outcome matched the prediction. In a spreadsheet, create columns: Timestamp, Market, Bet Amount, Odds, Outcome (Win/Loss). Then compute the win rate:

Win Rate (%) = (Number of Winning Bets) / (Total Number of Bets) × 100

As a benchmark, the average win rate for similar long-shot bets across all Polymarket markets is around 14%. For politics-focused markets, it’s 25%. If your sample shows a win rate significantly above these—especially above 30–40%—it’s a red flag.

Step 4: Compare Against Baseline Benchmarks

Now compare your calculated win rate with the expected baselines provided by the Anti-Corruption Data Collective:

• All Polymarket markets: 14% win rate.
• Politics-focused markets: 25% win rate.
• Military/defense long-shots: 52% win rate (according to the study).

If your target market’s long-shot win rate approaches or exceeds 50%, this is strong evidence of insider trading. For instance, a military market with a 48% win rate on long-shots warrants further investigation.

Step 5: Check for Concentrated Activity

Insider trading often involves a single wallet or a small group of wallets repeatedly winning. Examine the bettors behind the winning long-shots. If one address consistently places these bets across multiple military/defense markets and wins, that’s a telltale sign. You can use Polymarket’s wallet explorer tools or third-party services to map betting patterns. Look for:

• Same wallet placing multiple large, long-shot bets on similar events.
• Timing of bets just before major announcements (e.g., a $10,000 bet on a weapons-test failure hours before an official statement).
• Absence of corresponding bets on the opposite outcome (indicating one-sided informed play).

Step 6: Document and Validate Findings

To avoid false positives, validate your findings by cross-referencing with news about the market events. If you discover a pattern, save the data and take note of the specific markets, wallets, and timestamps. You can report your findings to researchers (like the Anti-Corruption Data Collective) or use the evidence to urge Polymarket to implement stricter KYC or surveillance measures. Remember, insider betting is currently legal on Polymarket due to its decentralized nature, but publicizing such patterns can help the community self-regulate.

Tips for Success

• Focus on niche military/defense markets: They have the highest signal-to-noise ratio for insider activity. Avoid oversaturated categories like entertainment or sports.
• Use automated scripts: Manually tracking hundreds of bets is tedious. Write a Python script to scrape Polymarket’s GraphQL API for trade history and odds.
• Beware of survivorship bias: Losing long-shot bets may have been cancelled or withdrawn. Ensure you’re using complete trade logs, not just successful ones.
• Consider the legal and ethical implications: While insider betting on Polymarket isn’t illegal, it undermines market integrity. Use your findings responsibly, and avoid engaging in such behavior yourself.
• Update your benchmarks regularly: The overall win rates may shift as the platform evolves. Revisit the Anti-Corruption Data Collective’s research for the latest figures.
• Share your methodology: Open-source your analysis to help others replicate your work and build a collective watchdog effort.