MIAX Delays PRIME Market Maker Contra-Party Functionality

Miami International Securities Exchange filed an immediately effective rule change with the Securities and Exchange Commission to delay a planned change to Rule 515A, covering the MIAX Price Improvement Mechanism and PRIME Solicitation Mechanism.

The August 26 notice says MIAX filed SR-MIAX-2026-35 on August 12. The delayed functionality would permit orders for accounts of market makers assigned in the applicable options class to be solicited as the contra party to an agency order submitted for execution in a PRIME or cPRIME auction.

MIAX originally indicated that the functionality would be implemented in the third quarter of 2026 and that it would publish a regulatory circular at least 30 days before launch. The exchange now says it has not issued that circular and proposes to delay implementation until the second quarter of 2027.

The filing says the delay is intended to give MIAX and its members enough time to complete the technical changes needed before implementation.

Why it matters

PRIME and cPRIME auctions are part of the execution workflow for options orders seeking price improvement or solicited liquidity. A delay changes the rollout calendar for brokers and options market makers that planned technology, supervision, and routing workflows around assigned market maker participation.

What to watch next

MIAX says it will issue a regulatory circular at least 30 days before implementing the functionality. Traders should watch that notice for the production date and any member testing requirements.