Normalize the question before comparing two markets

Two markets can share a headline and still ask different questions. Comparing their prices before aligning the details creates a gap that may not be tradable.

The cleanup work comes before the clever trade.

Write the event in plain language

For each contract, record the exact outcome, deadline, data source, unit, and threshold. Put the two descriptions side by side before looking for a percentage difference.

A count by a cutoff, a rate during a period, and a cumulative total can all sound similar in a headline while resolving under different facts.

Align the payoff

Check whether a winning share pays the same amount, whether one market has extra outcomes, and whether the positions settle on the same schedule. A price comparison that ignores payout shape is not comparing like with like.

Keep the definitions visible when you calculate an implied probability. The formula cannot repair a mismatched question.

Add the trading friction

Only after the event and payoff match should you subtract fees, spread, and the cost of carrying one position longer. If the difference disappears there, it was a description gap rather than an edge.

The useful question is not whether two prices look far apart. It is whether the contracts remain equivalent after you normalize the facts that decide settlement.

Further reading: Prices and order books · Resolution rules · Current fees.

Explore the markets: Open Polymarket (referral link).