Nasdaq PHLX amends Rule 3101 to lock Level 3 halt resumption at 4 a.m. ET
The amendment, effective immediately, applies to all PHLX equities and ties post-halt reopening to 4:00 a.m. ET despite upcoming 23-hour trading.
On September 25, 2026 Nasdaq PHLX LLC filed a proposed rule change, identified as Release No. 34-106585 and File No. SR-Phlx-2026-59, to amend Equity 4, Rule 3101. The amendment is effective immediately upon filing and would set the resumption time after a Level 3 market-wide circuit-breaker halt to 4:00 a.m. Eastern Time (ET) or later.
Current Rule 3101(b)(ii) requires a halt "for the remainder of the trading day" when a Level 3 decline (20% drop in the S&P 500) occurs. With the industry's planned shift to 23-hour, five-day trading sessions beginning December 6, 2026, that language could force an earlier reopening at 9:00 p.m. ET, the start of overnight trading. The proposed amendment deletes the existing phrasing and inserts language that explicitly ties reopening to 4:00 a.m. ET or later on the following trading day.
The Exchange states the change does not alter the market-wide circuit-breaker mechanism itself, but merely preserves the existing resumption practice across all self-regulatory organizations. The operative date will be set in coordination with other SROs and the Commission once operational feasibility is confirmed, and customers will be notified through Trader Alert.
The filing cites Section 19(b)(1) of the Securities Exchange Act of 1934, Rule 19b-4, and Section 6(b) and 6(b)(5) of the Act as statutory authority. The Commission is publishing this notice in the Federal Register (Vol. 91, No. 194, pages 64411-64413) to solicit comments from interested parties.
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