Compare Prediction Market Prices

What it means

In simple terms, a quoted price on a prediction market is the amount you would pay to buy a contract that pays $1 if a specific event happens. A Yes contract — an event contract that pays $1 if the event happens — priced at $0.62 implies a 62% probability according to that market.

The key thing to know is that different apps can show different prices for the same event. Those differences come from fees, order types, how liquidity is provided, and which users are active on each platform.

Why it matters

A small price difference can change your effective cost and your implied probability estimate. If you are comparing markets to form a judgment about an event, you want to make sure you are comparing like with like.

• Traders pay fees or face bid-ask spreads; those change the effective cost.
• Low liquidity can make a quoted price unreliable: a displayed price might be for a tiny trade only.
• Platforms with different user pools reflect different information and incentives.

How it works

Here's the basic idea of what creates price differences and how to compare them.

1. Quote type. Some platforms display the mid-price (the midpoint between best buy and sell offers). Others show the best available order (the price at which someone is willing to sell or buy right now). Mid-price is a convenience; the executable price may be the ask (more expensive) or the bid (cheaper).

2. Fees and rebates. Fees are charged in two common ways: a fee on realized profits (a percentage of gains) or a fee added to the trade price (a taker fee). If a platform charges a 2% fee on profits, the price quoted hasn’t yet accounted for that cost; your net expected return will be lower.

3. Liquidity and market structure. Some apps use an order book where users place buy and sell orders. Others use an automated market maker (AMM) that quotes prices based on a bonding curve. AMMs often widen prices as more of one side is bought. Low liquidity on either structure means a price may move a lot if you place a sizable trade.

4. User base and information. Different pools of participants have different knowledge, incentives, and risk tolerances. A platform with many political traders may price elections differently than a platform with few traders.

5. Settlement and resolution rules. If platforms resolve questions differently or have different resolution criteria, that affects price. Make sure you compare markets resolved to the same event definition.

When you compare prices across apps, follow these steps: verify the quoted type (mid vs executable), convert prices to implied probabilities, estimate fees you'd pay, and check the available quantity at the quoted price (liquidity). Use those adjusted numbers, not raw quotes, to compare.

A simple example

If a Yes contract costs 62¢ and pays $1 if the event happens, buying one contract costs $0.62. If the event happens, the contract pays $1, so the gain before fees is $0.38. If the event does not happen, the contract expires at $0, so the loss is $0.62.

A worked comparison across three apps (numbers rounded):

• Platform A: shows an executable ask price of $0.62, 1% taker fee on trade value, and a visible ask size of 100 contracts.
• Platform B: displays mid-price $0.61 but current best ask is $0.64, 0% taker fee but 5% fee on realized profits, and best ask size 10 contracts.
• Platform C: AMM price $0.63, visible liquidity such that buying 200 contracts would move the price to $0.67, and 2% taker fee.

Compare buying one contract on each platform.

Platform A: pay $0.62. Taker fee 1% of $0.62 = $0.0062. Total cost ≈ $0.6262. If event happens, payout $1. Net gain ≈ $0.3738.

Platform B: executable ask is $0.64 (not the $0.61 mid). No taker fee, but 5% fee on profit. Buy at $0.64. If event happens, gross gain $0.36. Fee on profit = 5% × $0.36 = $0.018. Net gain ≈ $0.342.

Platform C: AMM quotes $0.63 and taker fee 2%. Pay $0.63 + 2% of $0.63 = $0.0126. Total cost ≈ $0.6426. If event happens, net gain ≈ $0.3574.

Which is cheapest for one contract? Platform A effective cost ≈ $0.6262, B ≈ $0.64 (after profit fee accounted), C ≈ $0.6426. Platform A is best for a single contract in this example. But if you wanted to buy 100 contracts, Platform A and C show the available size; on Platform C the price would rise if you pressure the AMM, so that would change the comparison.

The simple point: raw quoted numbers (0.61 vs 0.62 vs 0.63) are only the start. Convert to the full effective cost after fees and slippage before you decide which is truly cheaper.

Common mistakes

Comparing mid-prices as if they are executable

Mid-prices are a useful midpoint reference, but they don’t tell you what price you will actually pay. The executable ask or bid matters for cost.

Ignoring fees or applying them the wrong way

Fees can be on trade value or on realized profit. Failing to apply the correct fee lowers the real expected return.

Overlooking liquidity and trade size

A price that looks attractive at a tiny quantity can change radically for larger orders. Always check how much is available at the quoted price.

Treating all platforms as identical markets

Different resolution rules, question wording, and participant pools mean prices reflect different information. Make sure you are truly comparing the same event.

Related concepts

• What Are Prediction Markets?
• What Are Yes/No Contracts?
• How to Read Prediction Market Prices
• What Is Implied Probability?