To safeguard users from price volatility when a new spot order book opens, OKX may implement different mechanisms depending on the type of token being listed. For new tokens requiring price discovery, the exchange often employs a periodic auction mechanism. For tokens with an existing index price that do not require price discovery, OKX may use a Pre-open session. The specific mechanism applied depends on real-time market conditions.
What Is the OKX Periodic Auction?
The OKX Periodic Auction allows traders to freely submit buy and sell orders at their desired prices before a new trading pair officially begins continuous trading. The trading system processes all submitted orders according to periodic auction rules and calculates an estimated opening price based on this order flow.
Which Tokens Use the Periodic Auction?
This mechanism is typically applied to newly listed trading pairs.
How Long Does the Periodic Auction Last?
The duration of the periodic auction varies based on the token type and market liquidity conditions. Generally, it lasts for a minimum of 10 minutes.
Supported Order Types During Periodic Auction
Only limit orders are supported during the periodic auction phase.
How Are Fees Calculated in Periodic Auction?
Upon conclusion of the periodic auction, the system charges taker fees for all orders matched during this period.
How Is the Estimated Opening Price Determined?
The estimated opening price must satisfy three conditions:
- It generates the highest possible trading volume.
- All buy orders above this estimated price, or sell orders below it, must be fully executable at this price.
- Both taker and maker orders at the estimated opening price must be fully matched.
Key Rules of the Periodic Auction
- Auction Phase (minimum 10 minutes): Users can place, cancel, or modify limit orders until the final 5 minutes of this phase. During the last 5 minutes, only new order submissions are permitted; order cancellations or modifications are disabled.
- Official Trading Launch: The final estimated opening price determined during the auction becomes the official opening price. Orders from the auction phase enter the matching system and are usually matched within 1 to 15 seconds. Unmatched orders remain in the order book and are executed based on standard continuous trading rules.
Who Can Participate in the Periodic Auction?
All OKX users are eligible to participate in the periodic auction mechanism.
Are There Order Limits During the Periodic Auction?
Yes, OKX imposes limits on the total order volume a user can place during the periodic auction. Specific details are provided in the individual token listing announcements.
Is API Trading Supported for the Periodic Auction?
Yes. Like other OKX trading products, users can place orders during the periodic auction via API. Market data and order book depth are accessible through REST API and WebSocket feeds. 👉 Explore advanced trading API documentation
What Information Do Users See During the Periodic Auction?
- Estimated Opening Price: The projected price for the trading pair.
- Matched Volume: The quantity of cryptocurrency successfully matched during the auction.
- Unmatched Volume: The quantity of cryptocurrency not matched during the auction process.
Why Might the Estimated Price Differ From the Official Chart Opening Price?
To provide additional trading context, after the periodic auction concludes, OKX may display the project team's suggested opening price at the start of continuous trading as the initial point on the trading chart. This price, often based on the project's own valuation, is for reference only. It is not determined by the auction mechanism and does not affect the execution price of user orders.
Understanding the Pre-open Mechanism
What Is the OKX Pre-open Session?
The Pre-open session on OKX allows users to place buy and sell limit orders at desired prices, within specific trading parameters, before the market officially opens. Its primary purpose is to provide liquidity for the trading pair, enhancing market continuity and stability. During Pre-open, buyers and sellers place limit orders around the index price, constrained by a price limit band. Buy orders must be placed below the index price (1 + X%) limit, and sell orders must be placed above the index price (1 - X%) limit. When the Pre-open session ends, the system uses the final index price to cancel invalid orders. Sell orders below the final index price and buy orders above it are deemed invalid and canceled. No orders are matched during Pre-open; unmatched orders that are not canceled remain in the order book for the continuous trading session.
Which Cryptocurrencies Use the Pre-open Mechanism?
Pre-open is applied to newly listed spot trading pairs that have an established index price.
How Long Does the Pre-open Session Last?
The duration depends on the token type and market liquidity. Typically, it lasts for a minimum of 30 minutes.
Supported Order Types During Pre-open
Only limit orders are supported during the Pre-open session.
How Are Fees Handled in Pre-open?
No fees are charged during or after the Pre-open session because no orders are matched or executed in this phase.
Key Rules of the Pre-open Session
- Pre-open Phase (typically minimum 30 minutes): Users can place, cancel, or modify limit orders throughout this session.
- Trading Commencement: The final index price from the Pre-open session is used to cancel invalid orders. Sell orders below this price and buy orders above it are canceled. Orders not canceled remain in the order book and are matched according to standard continuous trading rules.
Who Can Participate in Pre-open?
All OKX users can participate in the Pre-open session.
Are There Price Limits for Orders in Pre-open?
Yes, index price-based limits are applied. Buy orders must be below Index Price + X%. Sell orders must be above Index Price - X%. The X% acts as a buffer due to potential index price fluctuations during the session.
Example: If a token's index price is 1 and the price limit X% is set to 2%:
- Maximum allowed buy price: 1.02
- Minimum allowed sell price: 0.98
Can the Best Bid Price Be Higher Than the Best Ask Price in Pre-open?
Yes. Because price limits are based on a fluctuating index price, the best bid price can potentially be higher than the best ask price during the Pre-open session. These bid and ask prices will be visible in the order book.
Is API Trading Supported for Pre-open?
Yes. Users can place orders during the Pre-open session via API. Market data and order book depth are accessible through REST API and WebSocket feeds.
What Information Is displayed During the Pre-open?
- Current Index Price: The live index price for the cryptocurrency trading pair.
- Maximum Buy Price: The highest price at which a buy order will be accepted.
- Minimum Sell Price: The lowest price at which a sell order will be accepted.
Where Can I Find the Final Index Price Used for Order Cancellation?
OKX will display the final index price, which is used to cancel invalid orders and serves as the opening price on the K-line chart.
OKX is committed to providing a superior trading experience. We continuously monitor market developments and strive to improve the Pre-open mechanism, updating this documentation accordingly. Please check back for the latest updates.
Frequently Asked Questions
What is the main difference between Periodic Auction and Pre-open?
The key difference lies in their purpose. The Periodic Auction is designed for price discovery of new tokens without an established market price, ultimately matching orders at a single calculated opening price. Pre-open is for tokens with an existing index price; it collects liquidity without matching orders, and then invalid orders are canceled before continuous trading begins.
Can I cancel my order during the Periodic Auction?
Yes, but only until the last 5 minutes of the auction phase. In the final 5 minutes, you can only submit new orders; cancellation and modification functions are disabled to ensure a fair and stable conclusion to the price discovery process.
Why was my Pre-open order canceled?
Your Pre-open order was canceled because it was deemed invalid based on the final index price. When the Pre-open session ended, any sell order placed below the final index price or any buy order placed above it was automatically canceled by the system.
Are there any trading fees during the Pre-open session?
No. Since no orders are actually matched or executed during the Pre-open session, no trading fees are incurred. Fees only apply to orders that are successfully matched once continuous trading begins.
How does OKX determine the index price?
The index price is typically calculated based on a weighted average of the spot prices from several major exchanges. This aggregated price helps provide a fair and market-reflective value that is less susceptible to manipulation on a single platform.
Is there a minimum order amount for participating in these sessions?
While there might not be a specific minimum for the mechanisms themselves, standard trading minimums for the specific token pair likely apply. It's best to check the trading rules for the individual asset on the OKX website.