An arbitrage scan treats every book as interchangeable: it takes the best price on each side and stops there. Operators are not interchangeable. One manages its exposure per customer and acts on the accounts that win; another earns commission on matched wagers and does not care who wins. The shape of a pair is therefore the largest single driver of how long an account stays usable.
There is nothing in a price stream that says what an operator is. Anything inferred -- from a book's name, from how its prices behave, from how often it lands on the winning side -- would be a guess dressed as a fact. So the map below is editorial, it is dated, and it says whose read it is.
These definitions describe a CATEGORY of operator. They are stated once here and are not repeated against any individual book.
| Role | What the role means | Books |
|---|---|---|
| retail | A sportsbook that takes the other side of your bet and manages that exposure per customer. Winning and arbitrage accounts are commonly limited or closed -- this is the leg that costs account life. | 6 |
| offshore | An operator outside US licensing. It still books the bet against you and still limits, but it is not bound by a US regulator and there is no state avenue to appeal a limit or a voided wager. | 2 |
| exchange | A peer-to-peer market where the operator earns commission on matched wagers rather than positioning against the bettor, so a winning customer is not a losing position for the house. | 3 |
| prediction market | A CFTC-regulated event-contract market, not a sportsbook. You trade YES/NO contracts priced in cents against other participants, per-trade fees apply, and the quoted price is the top of an order book rather than a number an operator is offering to lay at your stake. | 2 |
Each book's basis is a licensing and business-model fact about that operator. The behavioral language belongs to the role above and stays there.
| Book | Role | Basis |
|---|---|---|
| BetMGM | retail | US-licensed retail sportsbook operating its own book against the customer. |
| BetOnline | offshore | Offshore operator serving US customers without US state licensing; books the bet against the customer. |
| BetOpenly | exchange | Peer-to-peer betting exchange: users set their own American-odds prices, another user takes the other side, and the operator takes a commission on winnings rather than booking the bet. Verified 2026-08-07 against the operator's public documentation. |
| BetRivers | retail | US-licensed retail sportsbook (Rush Street Interactive) operating its own book against the customer. |
| Bovada | offshore | Offshore operator serving US customers without US state licensing; books the bet against the customer. |
| Caesars | retail | Caesars Sportsbook, the Odds API's key for the William Hill US brand it succeeded. US-licensed retail book. |
| DraftKings | retail | US-licensed retail sportsbook operating its own book against the customer. |
| Fanatics | retail | US-licensed retail sportsbook operating its own book against the customer. |
| FanDuel | retail | US-licensed retail sportsbook operating its own book against the customer. |
| Kalshi | prediction market | CFTC-designated contract market listing binary event contracts priced in cents; trades are matched against other participants and carry per-trade fees. Verified 2026-08-07 against the operator's public documentation. |
| Novig | exchange | Peer-to-peer prediction exchange (Odds API us_ex region) earning commission on matched wagers rather than holding a position against the bettor. |
| Polymarket | prediction market | Binary event contracts priced in cents. US access runs through Polymarket US (QCX LLC), a CFTC-designated contract market whose amended Order of Designation the CFTC approved in November 2025. Verified 2026-08-07 against CFTC filings and the operator's public documentation. |
| ProphetX | exchange | Peer-to-peer sports betting exchange: participants post and take American-odds prices against each other and the operator earns commission on net winnings rather than holding a position. It received CFTC approval in June 2026, which changes who regulates it but not the operating model this taxonomy classifies -- the price is still American odds matched between two bettors, so it reads as an exchange rather than a cents-denominated event-contract market. Verified 2026-08-07 against the operator's public documentation. |
Every opportunity is labelled with the shape of its pair -- retail_vs_retail, retail_vs_exchange, retail_vs_prediction_market, and so on -- which is what names the leg a risk desk would act on.
One unclassified leg makes the whole pair unclassified. A shape is a claim about BOTH legs, so a half-known pair reports the honest thing rather than the half that happens to be knowable.
Lookup is exact on the feed's own key, with only case and surrounding whitespace normalized. There is no fuzzy matching and no prefix rule: a regional variant of a book's key is not that book until a human says it is.
Logged bets are grouped by the book they landed at, because limiting is a verdict on an account's cumulative pattern and never on a single bet.
Two round-stake facts are counted rather than one: whether a stake is a whole number of dollars, and whether it is also a multiple of five. They say different things -- a whole-dollar stake with an odd cents-free figure is the shape an optimiser produced, while a multiple of five is what a person chose -- and a single roundness figure would collapse the two and lose the part that carries the signature.
Below 5 entries at a book, the distribution and every percentage are withheld with the reason stated, while the plain counts still render. A share over three entries is a count with a percent sign on it, and it reads most confidently exactly where it is least supported.
Book roles are our own read of publicly observed operator behaviour, not a classification the books publish.
Roles last reviewed 2026-08-07. A book outside this map renders as unclassified and is never assigned a role by inference.
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This page describes how the tool works. It carries no price, no fair-value figure and no margin: every number on it is a fixed threshold or a count read out of the product's own configuration.