Market structure
Prediction markets, from first principles
An event contract is a claim that settles at a fixed value if a defined condition occurs. Its price between 0 and 1 corresponds to a probability — which is why these venues are often described as the cleanest available read on what a market believes. This page explains the mechanics; it publishes no prices, probabilities, contract counts, or volumes, because no market data provider is connected.
Spread monitor
Exchange probability vs. margin-adjusted posted price
Once an exchange feed and an odds feed are both connected, this module compares the two for each market. Where they diverge, the usual explanations are thin liquidity on the exchange or a stale posted price.
Live data integration coming soon
Exchange prices and contract volumes are only displayed when they come from a connected and permitted data source, alongside the provider name and retrieval time. No sample prices are shown here.
Structures
How the two structures differ
Categories, not companies. We do not name, rank, or link to individual venues.
Exchange / order book
- How prices form
- Participants post and match orders with each other.
- Cost to participate
- An explicit fee, charged separately from the price.
Because no operator takes the other side, the traded price reads more directly as a probability — subject to fees and to how much size is resting on the book.
Operator-priced sportsbook
- How prices form
- The operator posts a price and manages its own risk.
- Cost to participate
- A margin embedded inside the posted price.
The margin has to be removed before a posted price can be compared with a probability estimate. That arithmetic is covered in the learning hub.
Unregulated / offshore
- How prices form
- Varies, and is often not disclosed.
- Cost to participate
- Frequently undisclosed.
Included only so the structural categories are complete. We do not identify, rank, review, or link to individual venues in this category.
Mechanics
The four things that determine a contract's quality
Settlement source
A named, public, unambiguous source. If the contract language leaves room for interpretation, the price is not the only risk being taken.
Order-book depth
A quote is only as meaningful as the size behind it. Two cents of spread on a thin book carries far less information than a tight quote on a deep one.
Fee model
Explicit fees make the arithmetic simple: the estimated edge is your probability estimate minus the price minus the fee. Embedded margins hide the same cost inside the quote.
Resolution timeline
Capital committed until settlement has an opportunity cost. Long-dated contracts are more usefully evaluated on annualised terms than on raw payout.
Worked example
Turning a price into a probability
The arithmetic, shown on numbers chosen for the illustration. These are not quotes from any venue or market.
- Step 1 — ConvertTake a posted price of -150. Negative American prices convert with |p| / (|p| + 100), giving 60.0%.
- Step 2 — NormaliseDo the same for the other side. If it posts at +130, that is 43.5%. The two sum to 103.5%; the excess is the operator margin. Dividing each by the total gives 58.0% and 42.0%.
- Step 3 — CompareSet that normalised figure against the exchange quote for the same outcome. The difference between the two is the only number worth discussing — and it is the number this page will show once both feeds are connected.
Sources
No source is connected to this section yet. Nothing here should be read as a current factual claim.
The prices above are arbitrary teaching inputs, not observed quotes. You can run the same arithmetic on your own numbers in the calculators.
The Open
Market structure, decoded every morning
One brief: overnight repricing, cross-venue spreads, and one concept explained properly. No picks, no promos.