Portfolio Risk Calculator
Add your prediction market positions to see total risk, best/worst case P&L, and concentration warnings. Accounts for Kalshi and Polymarket fee structures.
Positions
Click "Add Position" to get started.
Portfolio Summary
Position Breakdown
| Name | Side | Cost | % Port | If Win | If Lose |
|---|
How Portfolio Risk Works in Prediction Markets
Every prediction market position has a defined maximum loss: the amount you paid to enter. If you buy 10 YES contracts at $0.40 each, your cost is $4.00 and your maximum loss is $4.00. Unlike stocks or options, there is no margin and no possibility of losing more than you invested.
The danger is not any single position — it is concentration. If three of your positions are all weather contracts in the same region, a single weather pattern can move all of them against you simultaneously. Similarly, putting most of your capital on one platform exposes you to platform-specific risks like outages or regulatory changes.
This calculator helps you visualize your total exposure, identify concentration risks, and understand the range of outcomes for your current portfolio. Use it alongside the Kelly Calculator to ensure each position is properly sized, and the Probability Calculator to verify each trade has positive expected value before adding it to your portfolio.
Frequently Asked Questions
How do I calculate my total risk in prediction markets?
Your maximum loss equals your total capital deployed — the sum of (price × quantity) for every position. Since contracts settle at $0 or $1, you can lose your entire investment on any single position. The portfolio calculator adds up all position costs to show your total capital at risk.
What is a good portfolio size for prediction markets?
Keep any single position under 5% of your total bankroll, and avoid having more than 25% in highly correlated positions (e.g., multiple weather contracts in the same region). Diversify across categories and platforms to reduce risk.
How do fees affect my portfolio returns?
Kalshi charges a 7% fee on net profits from winning trades. Polymarket has no explicit fees. Fees reduce your upside on winning positions but do not change your downside. The calculator accounts for fees in the "If Win" column so you see realistic net returns.
Should I diversify across prediction market platforms?
Yes. Spreading positions across Kalshi and Polymarket reduces platform-specific risks. The calculator flags when more than 80% of your capital is concentrated on a single platform.