Nasdaq PHLX scraps CORE FIX protocol after failing to attract participant interest

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

Nasdaq PHLX is removing every reference to its planned CORE FIX order entry protocol from Equity 4, abandoning a project it added to its rulebook in September 2025 and delayed three times. The filing is immediately effective. It confirms no functional change for participants, who keep OUCH, RASH, FLITE and FIX, and tidies a rulebook that has carried a dormant protocol for more than a year.

• PHLX proposes to delete all CORE FIX references from Equity 4 Rules 3100, 3301A, 3301B and 3307, including an online rulebook disclaimer.
• The exchange says it could not generate participant interest in CORE FIX and will abandon deployment rather than roll out an untested protocol.
• OUCH, RASH, FLITE and FIX remain the available and operative order entry protocols; the filing changes no order handling or participant rights.
• The change took effect immediately under Section 19b-4(f)(6); written comments to the SEC are due by December 3, 2026.
• A separate fee filing, SR-PHLX-2026-66, removes CORE FIX references from the Equity 7 pricing schedule.

Executive summary

Nasdaq PHLX LLC filed a proposed rule change with the SEC on October 30, 2026, published for comment on November 6, 2026 under Release No. 34-106840 and File No. SR-PHLX-2026-65, to amend Equity 4 and remove all references to the…

Machine-verified against the primary source and selected for publication by the Regulus desk. Not individually read by an editor. Lead briefings and anything our checks flag always are — how we review.