MX2 proposes rule amendment to keep 4 a.m. resume after Level 3 halt
The amendment, effective immediately upon filing on Oct. 19, 2026, binds MX2 and other SROs to resume trading at 4:00 a.m. ET after a Level 3 market-wide circuit-breaker halt despite upcoming 23-hour trading sessions.
On October 19, 2026, MX2 LLC filed with the SEC a proposed amendment to Rule 11.23(b)(2) of its trading-halt rules. The filing, identified as File No. SR-MX2-2026-09 and Release No. 34-106758, was published in the Federal Register on November 2, 2026 (FR Doc No. 2026-22264) and is effective immediately.
The amendment deletes the existing language that requires a halt "for the remainder of the trading day" after a Level 3 market-wide circuit-breaker (MWCB) decline and replaces it with language that trading in all stocks will be halted "until 4:00 a.m. Eastern Time on the following trading day."
The change is intended to preserve the current 4:00 a.m. ET resumption time when the industry expands to 23-hour, five-day trading sessions ("23/5 Trading"). MX2 notes that several exchanges, including its affiliate MEMX, plan to begin overnight sessions from 9:00 p.m. to 4:00 a.m. ET on December 6, 2026. Without the amendment, the existing rule would trigger an earlier reopen at 9:00 p.m., shortening the cooling-off period the MWCB mechanism is designed to provide.
The proposal is made under Section 19(b)(1) of the Securities Exchange Act of 1934 and Rule 19b-4, and MX2 cites Section 6(b)(5) as the statutory basis for ensuring a just and equitable market. The Commission has opened a comment period for interested parties.
Further reading