Auction Summary Message Fields (BYX Equities, BZX Equities, and Options Only)
Auction Summary messages are used to disseminate the results of an auction of a Cboe listed security on BZX, the results of an Opening or Re-Opening of any options series on C1, and for Periodic Auctions on BYX.
Cboe Auction Summary messages support the Cboe Opening, Closing, Halt and IPO Auctions on the BZX Exchange. An Auction Summary message for each Cboe listed security is sent at the conclusion of its Opening Auction at 9:30 a.m. and represents the Cboe official opening price. A Closing Auction Summary message for each Cboe listed security is sent at the conclusion of its closing auction at 4:00 p.m. and represents the Cboe official closing price. An IPO Auction Summary message for each Cboe listed security is sent at the conclusion of the IPO Auction and represents the official Cboe IPO opening price.
Auction Summary messages are also used in support of Opening and Re-Openings on the Cboe Options Exchange, including those for both GTH and RTH sessions. These messages indicate the price and size executed in such an Opening or Re-Opening. Refer to the Cboe Titanium U.S. Options Opening Process specification for more information.
An Auction Summary message will be sent for Cboe Market Close (CMC) once the official closing price for each security is available. The Price and Shares field will indicate the price of the CMC matching session and the number of shares that were executed. If the official closing price is updated after its initial publication, then another Auction Summary message will be disseminated to reflect the updated price of the CMC matching session.
On the BYX Exchange, Auction Summary messages will be sent out upon conclusion of a Periodic Auction. Auction Summary messages will provide the results of the Periodic Auction, including the price and shares executed.
The Auction Summary message has the following format:
| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field. |
| Message Type | 1 | 1 | 0x96 | Auction Summary message |
| Time offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp. |
| Stock Symbol | 6 | 8 | Printable ASCII | Stock Symbol right padded with spaces. |
| Auction Type | 14 | 1 | Alphanumeric |
|
| Price | 15 | 8 | Binary Long Price | Auction price or CMC match price. |
| Shares/Contracts | 23 | 4 | Binary | Cumulative number of shares/contracts executed during the auction or CMC matching. |
| Total Length = 27 bytes | ||||