Reminder - Cboe EDGX Equities Expands Trading Hours

Effective December 6, 2026 (trade date December 7, 2026), Cboe EDGX Equities Exchange (EDGX) will expand trading hours as outlined below to follow a 23x5 schedule. Effective trade date November 2, 2026, supporting changes will be made related to market data, application restart times, Execution IDs, and Trade Data/Trade Detail, as outlined below.

Changes to the Cboe One U.S. Equities feed to accommodate the expanded trading hours are outlined in this notice. All times outlined in this notice are ET.

Upon the effective date, EDGX trading hours will begin at 9:00 p.m. on Sundays and end at 8:00 p.m. on Fridays, as outlined below. Trades during the Overnight Trading Session (OTS) occurring before midnight will be marked with the Trade Date of the following trading day.

A new "Hold Early Orders Until" port attribute will be added to the FIX and BOE3 order entry protocols for all Cboe U.S. Equities Exchanges. If configured, the system will use the later of the start time specified or the start time of the TimeInForce value specified on the order. Start times may be set in 1/2 hour increments up to 9:00 a.m.

The "Early Trading Session Opt-Out" and "Hold Early to 7am" port attributes will be sunset on trade date December 7, 2026. Members using one of the two sunsetting port attributes who do not provide further instructions to the Cboe Trade Desk will have the new "Hold Early Orders Until" port attribute automatically added to their sessions with a configured start time that is commensurate to the legacy attribute being used.

To make port attribute changes, Members can use the Modify tab in the Logical Port Request tool in the Cboe Customer Web Portal.

The Time Reference message will be extended to BZX and EDGX effective trade date November 2, 2026 on the U.S. Equities Multicast PITCH, TCP PITCH, TOP, and Last Sale feeds.

The Time message will be extended from 6 bytes to 10 bytes with the addition of the Epoch Time field effective trade date November 2, 2026 on the U.S. Equities Multicast PITCH feed for BZX and EDGX only.

Effective trade date November 2, 2026, the Last Update Timestamp, Timestamp, and Transaction Time fields on the U.S. Equities Summary Depth Feed will be updated to contain the number of nanoseconds since epoch instead of the number of nanoseconds since midnight.

See the specifications linked below for more details. Cboe One feed changes are outlined in this notice.

Effective trade date November 2, 2026, the U.S. Equities Trade Data and Trade Detail files will include "Order Entry Date" as the first column.

Effective trade date November 2, 2026, BZX and EDGX Equities Exchanges will update the format of ExecID (FIX Tag 17) to start with 1 instead of 0 when there is a matched trade on the local Cboe book. This change will impact all market data feeds, order entry fills, and trade data files.

On the effective date, EDGX Self-Clearing Members will have their self-cleared MPIDs automatically enabled for the OTS, unless the firm otherwise notifies the Exchange in writing.

All Non-Clearing Members must submit an EDGX Overnight Trading Session Clearing Letter of Guarantee to [email protected] for any MPIDs they want enabled during the OTS. The OTS Guarantee must be signed by the Member's Clearing Firm authorizing the Member to participate in that session.

Membership Services will review the submitted Letter of Guarantee to confirm it is properly completed and signed by an authorized representative of the Clearing Firm. Once the guarantee has been reviewed and approved, Membership Services will enable the Member's MPIDs for OTS eligibility under the associated Clearing Firm's NSCC number. Members should note that until this approval and activation process is complete, they will not be permitted to enter orders or execute trades during the OTS, even if they are otherwise approved to trade during RTH.

Members are encouraged to submit their Letter of Guarantee well in advance of the December 6, 2026 OTS launch to allow sufficient time for review and activation. Members with multiple Clearing Firms, or those trading under more than one MPID, should ensure a separate, properly executed Letter of Guarantee is submitted for each Clearing Member relationship under which they intend to trade overnight.

If a Member has questions about the submission process, required signatories, or the status of a pending Letter of Guarantee, they should contact Membership Services directly at [email protected].

The testing opportunities and rollout schedule is as follows.

For each weekend test listed above, Cboe EDGX will start systems between 10:10 and 10:22 p.m. A Queueing Period will run from 10:55 p.m. to 11:00 p.m. At 11:00 p.m., Overnight Trading on EDGX will begin and EDGX will continue through a regular trading schedule until the test concludes. Weekend testing concludes on Saturday with a regular session close at 12:00 p.m. and a post-market session close at 1:00 p.m. Cboe will generate test data and submit trades/quotes to the SIPs during these scheduled weekend tests. All production symbols will be supported.

Cboe BZX Exchange will not have updated trading hours but will publish LULD Bands and may declare Regulatory Halts on BZX-listed securities during weekend tests.

Cboe will have staffing and support available from 10:30 p.m. Friday to 12:30 a.m. Saturday on weekend test dates. All other testing is unattended, and any questions received will be answered the following week.

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