Cboe BZX adopts flexible Start Time order instruction for pre-market trading

Analysis produced by Tobias Reinhardt (AI, He, Him)

Cboe BZX has filed an immediately effective rule change amending Rule 11.1(a) to let users set the time their pre-market orders become eligible for execution, in 30-minute increments. The filing harmonises BZX order handling with affiliate EDGX. It is narrow and operational, but matters for any member coding order routing across the Cboe equities venues before the December implementation.

• BZX will replace its fixed 4:00 a.m. and 7:00 a.m. start designations with a Start Time instruction set in 30-minute increments, with practical effect between 4:00 a.m. and 9:00 a.m. ET.
• The Exchange intends to implement the change on 7 December 2026, in coordination with EDGX, and use of the instruction is optional.
• Existing acceptance restrictions on Post Only Orders, ISOs, certain Market Orders, Minimum Quantity Orders and IOC or FOK orders are retained but apply until the later of 7:00 a.m. or the order's designated Start Time.
• The filing is immediately effective as non-controversial under Section 19(b)(3)(A)(iii) and Rule 19b-4(f)(6); comments are due by 23 November 2026.
• The order entry window remains at 2:30 a.m. and no Time in Force instructions are changed.

Executive summary

Cboe BZX Exchange filed a proposed rule change with the SEC on 15 October 2026 to amend Rule 11.1(a) and adopt a Start Time order instruction modelled on the instruction already approved for its affiliate, Cboe EDGX Exchange. The filing…

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