OKX call auction and pre-open mechanism

Published on Apr 27, 2018Updated on Aug 14, 20258 min read10

Introduction

To protect users from price volatility associated with the opening of a new spot orderbook, OKX may employ varying mechanisms depending on the types of tokens being listed. For crypto tokens that are new to market and require price discovery, OKX may utilize the call auction mechanism. For crypto tokens with an established index price and do not require price discovery, OKX may implement the Pre-open mechanism. The exact mechanism employed will depend on actual market conditions.

Call Auction

1. What is OKX call auction?

OKX call auction allows you to freely submit buy and sell orders at your desired prices before a new trading pair officially begins trading. The trading system processes all submissions according to call auction rules and calculates an indicative opening price based on these submissions.

2. Which crypto will have a call auction?

Call auctions will be used for newly listed trading pairs.

3. How long does the call auction last?

The duration of the call auction depends on the specific crypto and market liquidity. Typically, the call auction lasts at least 10 minutes.

4. What order types are supported during the call auction?

Only limit orders are supported during the call auction.

5. How are the fees charged during the call auction?

At the end of the call auction, the system charges a taker fee for orders executed during this period.

6. How is the indicative opening price determined?

The indicative opening price must meet the following three conditions:

  • It generates the highest trading volume.

  • All buy orders above the indicative opening price or all sell orders below the indicative opening price must be fully executed at the indicative opening price.

  • Either taker or maker of the orders at the indicative opening price must be fully executed.

7. What are the rules for the call auction?

  • Call auction phase (which will last for at least 10 minutes): you can place, cancel, or modify limit orders up to the final five minutes. During the final five minutes of the call auction, you will only be able to place but not cancel or modify orders.

  • Live trading phase: the final indicative opening price calculated based on the price discovery during the call auction is used as the official opening price. After the live trading begins, the matched orders from the call auction phase will enter the matching engine and be executed typically within 1 to 15 seconds. The unmatched orders from the call auction will remain on the orderbook and be executed based on orderbook trading rules.

8. Who can participate in the call auction ?

All OKX users would be able to participate in the call auction.

9. Is there a limit of orders users can place during the call auction

Yes, we apply a limit on the total size of orders that applicable users can place during the call auction. Please refer to the specific listing announcement for more details.

10. Is the call auction supported through the API?

Yes. Just like other trading products, you can place orders during the call auction via API. You can also access market data and order book depth through the REST API and WebSocket feed. For more information, please refer to our API documentation.

11. What information is provided to users during the call auction?

  • Indicative opening price: the estimated price for the trading pair.

  • Matched orders volume: the quantity of crypto successfully matched during the call auction.

  • Unmatched orders volume: the quantity of crypto not matched during the call auction.

12. Why is the indicative price different from the opening price as shown on the trading graph?

In order to provide more trading information, following the end of the call auction, OKX will display the project team's opening price at the commencement of continuous trading as the initial price of the trading chart. The project team's opening price is provided by the token project team usually based on the valuation of the project. This project team's opening price is displayed for information purpose only, and is not determined by the call auction mechanism, and will not impact the prices where you will execute the orders.

Pre-open

1. What is OKX Pre-open ?

OKX Pre-open allows you to submit buy and sell orders at your desired prices according to certain trading parameters before the commencement of official market trading. The main purpose of a Pre-open session is to provide liquidity to the trading pair to enhance the continuity and stability of market trading. During the Pre-open session, the buyers and sellers submit limit order around the index price, restricted by index price price limit. Buy orders must be lower than index price*(1 + X%) price limit; sell orders must be higher than index price*(1 - X%) price limit. At the end of the Pre-open session, the final index price is used to cancel invalid orders. Sell orders that are lower than the index price and the buy orders that are higher than the index price would be considered invalid and will be cancelled. There will be no execution of the orders during the Pre-open session, and uncancelled orders will be kept in the order book for continuous trading. Once live trading starts, the uncancelled orders placed during the Pre-open session will be kept in the orderbook.


2. Which cryptocurrencies will be subject to a Pre-open session?

Pre-Ope will be used for newly listed spot trading pairs that have index prices. For details on the index prices, please visit Spot Index Price.

3. How long does the Pre-open session last?

The duration of the Pre-open depends on the specific cryptocurrency and market liquidity. Typically, the Pre-open session lasts at least 30 minutes.

4. What order types are supported during the Pre-open session?

Only limit orders are supported during the Pre-open session.

5. How are the fees charged during the Pre-open session?

There will be no fees charged during and after the Pre-open session as no orders are matched or executed.

6. What are the rules for the Pre-open session?

  • Pre-open session (which will typically last for at least 30 minutes): you can place, cancel, or modify limit orders

  • Live-trading phase: the final index price at the end of Pre-open session will be used to cancel invalid orders. Sell orders that are lower than the index price and the buy orders that are higher than the index price would be cancelled. The uncancelled orders will remain on the orderbook and be executed based on orderbook trading rules.


7. Who can participate in the Pre-open session?

All OKX users would be able to participate in the Pre-open session.

8. Is there a price limit on the orders during the Pre-open session?

Yes, price limit based on index price will be applied. Bid orders must be lower than index price + X%. Ask orders must be higher than index price - X%. X% is used as buffer around index price as index price may change during the Pre-open session.

For example, when the index price of the token is 1 and the X% price limit is set to be 2%. The price limits allow traders to have buffer in their quotes as index price will move during the Pre-open session.

Maximum bid price: 1.02

Minimum ask price: 0.98

9. Can the best bid price be higher than the best ask price during the Pre-open session?

Yes, as the price limit is set based on index price and index prices are moving during the Pre-open session, it is possible to have the best bid price higher than the best ask price during the Pre-open session. Prices of bid and ask orders are displayed on the orderbook.

10. Is the Pre-open session supported through the API?

Yes. Just like other trading products, you can place orders during the Pre-open session via API. You can also access market data and order book depth through the REST API and WebSocket feed. For more information, please refer to our API documentation.

11. What information is provided to users during the Pre-open session?

  • Current Index Price: the current index price for the cryptocurrency trading pair

  • Maximum Bid Price: the highest price of bid orders that can be accepted

  • Minimum Ask Price: the lowest price of ask orders that can be accepted


12. Where can I see the final index price used to cancel orders?

OKX will display the final index price, which will be used to cancel orders and will be used as the initial price of the K-line chart.


OKX is committed to providing a better trading experience for users. We will closely monitor market activities and keep improving the Pre-open mechanism and will provide timely updates to this document . Please revisit this page to view the updates.

Disclaimer

This content is provided for informational purposes only and it is not intended to provide (i) investment advice or an investment recommendation; (ii) an offer or solicitation to buy, sell, or hold digital assets, or (iii) financial, accounting, legal, or tax advice. Digital asset holdings, including stablecoins and NFTs, involve a high degree of risk and can fluctuate greatly. You should carefully consider whether trading or holding digital assets is suitable for you in light of your financial condition. Please consult your legal/tax/investment professional for questions about your specific circumstances. Information (including market data and statistical information, if any) appearing in this post is for general information purposes only. While all reasonable care has been taken in preparing this data and graphs, no responsibility or liability is accepted for any errors of fact or omission expressed herein. © 2025 OKX TR Kripto Varlık Alım Satım Platformu A.Ş.

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