A stale quote can look like an edge for one expensive second

A price gap can look like free money when one screen updates slower than the other.

Before calling it an edge, check whether both quotes are fresh, executable, and tied to the same event definition.

Put timestamps beside prices

Record the quote time, retrieval time, side, size, and market identifier. A displayed price without a timestamp is incomplete evidence.

Suppose one venue shows a 48-cent ask from a few seconds ago while a second venue is already at 54 cents. The apparent six-cent spread may be a stale observation, not a trade you can still make.

Match the contracts

Compare outcome wording, cutoff, resolution source, and cancellation treatment. Similar names do not guarantee equivalent payouts.

Then estimate the time needed to submit, receive confirmation, and hedge. If the first leg fills but the second quote moves, the position is directional until you complete the hedge.

Log what did not fill

Include canceled orders, rejections, partial fills, and failed requests in the review. A strategy that counts only completed pairs can hide the moments it carried exposure.

The useful question is not whether two screens differ. It is whether both prices survive the same timestamp, size, contract, and execution path.

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

Explore the markets: Open Polymarket (referral link).