Prediction Market Bankroll Management: Never Blow Up Your Account

The primary factor behind unsuccessful forecasters in prediction markets isn't inaccurate forecasting — it's inadequate bankroll discipline. An astute probability assessment becomes worthless if a single losing run depletes your entire balance. This guide outlines the methodology that safeguards against such ruin.

The Kelly Criterion: The Mathematical Foundation

Kelly Criterion establishes the theoretically ideal percentage of your bankroll to allocate to each wager: f = (bp - q) / b

• b = net odds received (e.g., if YES costs 0.40, b = 1.5)
• p = your probability estimate
• q = 1 - p
• Result: optimal fraction of bankroll for this position

In practice: use half-Kelly. Whilst Kelly delivers mathematical optimality under perfect probability knowledge, real-world estimates carry inherent uncertainty, making half-Kelly the superior choice for risk-adjusted performance.

Hard Rules: Never Break These

• Maximum 5% of bankroll per single position — no exceptions regardless of conviction
• Maximum 25% of bankroll in any single correlated cluster — e.g., all US election markets
• Stop-loss: if you lose 25% of your starting bankroll in a month, stop trading for the rest of the month
• Never add to a losing position to "average down" — reevaluate the fundamental thesis first

Drawdown Recovery

Inevitable downturns occur even amongst traders with genuine edge. Following a 20% decline in account value, scale back position allocations by half until you reach your previous peak. This approach ensures a temporary setback doesn't spiral into account destruction.

FAQ

How much starting capital do I need for serious prediction market trading?

$500-1,000 furnishes adequate resources to build a diversified portfolio spanning 10-20 positions using half-Kelly methodology. Accounts below $100 face constraints that undermine systematic position sizing discipline.

What should I do after a winning streak?

Maintain heightened scrutiny rather than relaxing standards. Consecutive wins breed complacency and misjudgement. Adhere to your disciplined sizing framework irrespective of recent success.