Vig

Also called vigorish · juice · house edge

The margin built into quoted prices; on an order-driven exchange the equivalent is the overround plus the venue fee.

The word comes from bookmaking, where a house sets prices so the implied probabilities across all outcomes sum above one hundred percent and keeps the difference. It is worth being precise about how much of that translates here, because the answer is: less than people assume, and in a different form.

Polymarket and Kalshi are order-driven exchanges. There is no house setting a line — you trade against other participants' resting orders, and the quoted numbers are prices rather than odds. The margin you pay therefore comes from two places, both of them measurable, instead of one opaque one. The first is the overround in the resting book, which is what liquidity providers charge for quoting. The second is the explicit venue fee: on Kalshi a published per-contract charge that peaks near the middle of the price range, and on Polymarket no trading fee at all, leaving on-chain costs and spread.

Because both components are visible, both are already netted out of anything this site calls an edge. If a number here is described as net, the fee model has been applied to every leg; if it is described as gross, it has not, and it is labeled as a signal rather than an opportunity.

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Definitions describe how Polymarket and Kalshi behave and how WhaleTracks models them; venue rules and fee schedules can change, so confirm anything you size a position on with the venue itself. WhaleTracks is informational analytics, not financial advice. Past performance does not guarantee future results.