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How prediction markets actually work
Edge, vig, position sizing and calibration — written for people putting real money on Polymarket, Kalshi and sportsbooks. No picks, no hype, and every number worked through.
Getting started
How to read a prediction market price
What 63c actually means, how it maps to odds you already know, and the four things the number is not telling you.
Read article· 2 minPrediction market glossary
The terms you need to read a market, a price and a report — defined plainly, with the ones that actually cost money flagged.
Read article· 3 minStrategy
How to find edge on a prediction market
Edge is the gap between the market's price and the real probability, minus what it costs to trade. Here is how to measure each of those three parts.
Read article· 4 minWhy most prediction market traders lose
It is rarely bad analysis. It is six specific, boring, entirely fixable habits — and the fixes are unglamorous.
Read article· 3 minWhat the vig really costs you
The house edge is not the 5% you think it is. Here is how to strip the vig out of a price, and what the real number does to a break-even hit rate.
Read article· 3 minPosition sizing without going broke
Finding an edge is half the job. Kelly tells you how much to put behind it — and why almost everyone should bet a fraction of what it says.
Read article· 3 minAre you actually any good? Measuring it properly
Win rate tells you almost nothing. Brier score and a calibration curve tell you whether your probabilities mean anything — and how many you need first.
Read article· 3 minCopy trading and the entry-gap problem
Following a profitable wallet sounds like free alpha. The price has already moved by the time you see it — here is how to tell whether the copy is still worth taking.
Read article· 3 minComparisons
Stop doing this arithmetic by hand
Paste any market and Sharply does the whole process — matches the contract, de-vigs the price, researches the question, and tells you what edge is left after costs.
Analyze a bet — $1