Who sets the price, and who follows

Sportsbooks fall into two camps. A few take very large bets, welcome winning customers, and run on thin margins and enormous volume. Their prices move first and are most likely to be right. The rest largely watch those numbers and copy them, with a wider margin and a friendlier app.

Why the difference exists

A book that accepts big informed money finds out immediately when its number is wrong, because someone bets it. That feedback keeps the price accurate. A book that limits or bans winners never gets the feedback, so its numbers drift — and drift is exactly where your edge lives.

This app's reference books

Fair value here is a weighted blend, not a flat average. Pinnacle carries the most weight, because it is the closest thing the industry has to a source of truth. Next come three exchanges — Kalshi, Polymarket and Novig — then BetOnline, and finally the Betfair exchange, which counts least because its depth is in European football and racing rather than the leagues this app carries. Circa is widely regarded as sharp too, and is coming to the app soon.

Some of those references are not places this app will send you. Pinnacle and the Betfair exchange do not take bets from US customers at all. BetOnline does — it is offshore and it accepts American action without much fuss — but it holds no state licence, which means no regulator to appeal to if a withdrawal stops arriving. Reading a price is a different act from sending money somewhere, and those books are marked REFERENCE for that reason. The exchanges are not: Kalshi, Polymarket and Novig both help set the number and are somewhere you can actually bet.

Exchanges and peer-to-peer books

Betfair, Novig, ProphetX and prediction markets like Polymarket and Kalshi are marketplaces rather than traditional books — users take both sides and the operator takes a commission instead of building a margin into the price. Sharp bettors use them heavily, so heavy money on one side is a genuine signal. Six thousand dollars sitting on a player prop tells you something a recreational book's price does not.

That structure is also why three of them help set fair value here. Nobody at an exchange is shading a number to balance the house's position, because there is no house. When real money is matched on both sides, the price is not somebody's opinion with a margin bolted on — it is the market's own number, which is the same property that makes Pinnacle worth listening to.

The catch, and what we do about it

The same mechanism fails when nobody has shown up. An exchange quotes whatever the last unmatched order says, so a market the rest of the world has at -110 can read -1000, or +1000, with a single dollar behind it. That is not an opinion. It is the absence of one wearing a price — and if you average it into fair value, every number on that market goes wrong, including the ones at other books.

So the three exchanges are judged market by market rather than trusted or distrusted as a whole. On a market where their price sits in line with the rest of the board, they count, at a weight just below Pinnacle. On a market where one of them is wildly out of step, it is dropped from fair value entirely for that market — not down-weighted, dropped.