Cboe BYX Exchange expands Rule 11.17 to cover overnight price bands

On September 24, 2026 Cboe BYX Exchange filed a non-controversial proposed rule change (Release No. 34-106623; File No. SR-CboeBYX-2026-035) to amend Rule 11.17, "Clearly Erroneous Executions." The filing was published in the Federal Register on October 7, 2026 (FR Doc No. 2026-20798) and is effective immediately.

The amendment aligns Rule 11.17 with the Securities and Exchange Commission's August 5, 2026 approval of Overnight Protected Bands under the Limit Up-Limit Down (LULD) Plan for 23-hour, 5-day trading. The Commission's order established temporary static overnight price bands set at 20 % above and below two reference points for the period from 9:00 p.m. ET through 4:00 a.m. ET.

The Exchange proposes to replace "Regular Trading Hours" with "LULD Protected Hours," a term that will now encompass both regular and overnight protected hours. It also adds definitions for "Overnight Price Bands" and "Overnight Percentage Parameter" and updates Rule 11.17(c)(1)(B) to reference the overnight parameter when evaluating price deviations.

Additional language changes expand the scope of the "eligible for review" provision in Rule 11.17(c)(2) and related subsections to include transactions in NMS stocks not subject to the LULD Plan that occur during overnight protected hours. The numerical guidelines for such transactions will mirror those already applied to early-trading, pre-opening, and after-hours sessions.

The Commission is soliciting comments on the proposal. All filings, including Exhibit 5 containing the revised rule text, are available on the SEC's website and the Exchange's website.