04 Order Book Liquidity
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Quick Answer
An order book lists the prices and sizes at which traders are willing to buy or sell. On Opinion.trade, check the best bid, best ask, spread and depth before submitting an order. A tight spread with meaningful size usually makes entry and exit easier; a wide or shallow book can make the displayed probability expensive to trade.
Key Takeaways
- The best bid is the highest visible buy price; the best ask is the lowest visible sell price.
spread = best ask − best bid; a wider spread raises the cost of immediate execution.- Depth matters as much as the top price because a larger order may fill across several levels.
- Total execution cost can include the trading fee, spread and price impact.
- A limit order gives price control but may fill partially or not at all.
A 30-Second Pre-Trade Check
Why There Are Two Prices
Beginners often expect a market to have one price. In reality, many markets have at least two visible prices:- Bid: the highest price someone is willing to buy at.
- Ask: the lowest price someone is willing to sell at.
What the Order Book Shows
The order book shows market interest at different prices. For example, in a Yes market:- Some users may be willing to buy Yes at 0.60.
- Some users may be willing to sell Yes at 0.66.
- More orders may sit below or above those prices.
Why Liquidity Matters
Liquidity is what makes a market usable. A liquid prediction market usually has:- More participants
- More orders
- Tighter spreads
- Easier entry and exit
- Prices that are harder to move accidentally
Spread, Price Impact and Fees Are Different
These three costs are related but not interchangeable:- Spread is the gap between the best bid and ask.
- Price impact is the change in your average fill when the order uses multiple price levels.
- Trading fee is the platform charge shown in the order preview. Under Opinion’s current policy, takers pay while makers are not charged.
A Simple Opinion.trade Example
Suppose the best bid for Yes is0.62 and the best ask is 0.66. The visible spread is 0.04, or four cents per share.
If only 50 shares are offered at 0.66 and the next 100 are offered at 0.69, a market buy for 120 shares cannot fill entirely at 0.66. Part of it may execute at the higher level, so the average fill price is worse than the first ask you saw. That difference is price impact.
The example is hypothetical. Live prices, depth and fees change continuously; use the order book and confirmation screen for the current numbers.
Market Order vs Limit Order
Two basic order types matter: Market order:- Executes quickly against available liquidity.
- Useful when speed matters.
- Can be more expensive in thin markets.
- Sets the price you are willing to trade at.
- May not fill immediately.
- Gives more control over entry price.
What Beginners Should Check
Before entering a prediction market, check:- What is the best bid?
- What is the best ask?
- How wide is the spread?
- Is there enough size near the current price?
- Could I exit if I needed to?
How to Read the Opinion.trade Order Book
Opinion displays participant orders rather than one operator-set quote. Before placing an order:- Confirm that you are looking at the intended outcome, such as Yes rather than No.
- Compare the best bid and ask and calculate the spread.
- Check the size available at the first several price levels.
- Compare that depth with your intended order size.
- Decide whether immediate execution or a resting limit price fits your goal.
- Review the estimated fill and fee before confirming.
What to Watch
When a market looks promising but the order book looks thin:- Top-of-book size. How many shares are available at the best bid and best ask? Small size means your trade eats through multiple levels.
- Spread as a percentage. A 1-cent spread on a 50-cent contract is 2%. The same cent at 10 cents is 10%.
- Depth chart shape. A flat depth chart deeper in the book is healthier than all-or-nothing at one price.
- Event timing. Liquidity and volatility can change sharply around scheduled announcements, kickoff or other catalysts.
Conclusion
Liquidity helps determine whether a displayed price is actionable and how costly entry or exit may be. Reading the order book does not remove risk, but it gives users better information about spread, depth and likely execution before they place an order. Check the live Opinion.trade app for current markets and rules.FAQ
What is a bid?
What is a bid?
A bid is the highest price someone is currently willing to pay to buy.
What is an ask?
What is an ask?
An ask is the lowest price someone is currently willing to accept to sell.
What is spread?
What is spread?
Spread is the difference between the best bid and best ask.
Why should beginners care about liquidity?
Why should beginners care about liquidity?
Because low liquidity can mean wider spreads, harder exits, and prices that may be less reliable as probability signals.
Sources & References
- OPINION Docs — Understanding the order book — Opinion’s bid, ask, spread, limit-order and partial-fill mechanics
- OPINION Docs — Fees — Current maker/taker policy, fee curve and minimums
- Investopedia — Order Book — General order-book definition
- Investopedia — Bid-Ask Spread — General spread definition