Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934 (“Act”),^[1] and Rule 19b-4 thereunder,^[2] notice is hereby given that on July 27, 2026, Miami International Securities Exchange, LLC (“MIAX” or “Exchange”) filed with the Securities and Exchange Commission (“Commission”) a proposed rule change as described in Items I and II below, which Items have been prepared by the Exchange. The Commission is publishing this notice to solicit comments on the proposed rule change from interested persons.

I. Self-Regulatory Organization's Statement of the Terms of Substance of the Proposed Rule Change

The Exchange proposes to amend Exchange Rule 515A, MIAX Price Improvement Mechanism (“PRIME”) and PRIME Solicitation Mechanism, related to Request for Response (“RFR”) messages.

The text of the proposed rule change is available on the Exchange's website at www.miaxglobal.com/​markets/​us-options/​miax-options/​rule-filings and at MIAX's principal office.

II. Self-Regulatory Organization's Statement of the Purpose of, and Statutory Basis for, the Proposed Rule Change

In its filing with the Commission, the Exchange included statements concerning the purpose of and basis for the proposed rule change and discussed any comments it received on the proposed rule change. The text of these statements may be examined at the places specified in Item IV below. The Exchange has prepared summaries, set forth in sections A, B, and C below, of the most significant aspects of such statements.

A. Self-Regulatory Organization's Statement of the Purpose of, and Statutory Basis for, the Proposed Rule Change

1. Purpose

The Exchange proposes to amend Exchange Rule 515A related to PRIME functionality. PRIME is a process by which a Member ^[3] may electronically submit for execution (“Auction”) an order it represents as agent (“Agency Order”) against principal interest, and/or an Agency Order against solicited interest.^[4] A Member (the “Initiating Member”) may initiate an Auction provided all of the following are met: (i) the Agency Order is in a class designated as eligible for PRIME as determined by the Exchange and within the designated Auction order eligibility size parameters as such size parameters are determined by the Exchange; (ii) the Initiating Member must stop the entire Agency Order as principal or with a solicited order at the better of the NBBO ^[5] or the Agency Order's limit price (if the order is a limit order); and (iii) with respect to Agency Orders that have a size of less than 50 contracts, if at the time of receipt of the Agency Order, the NBBO has a bid/ask differential of $0.01, the System ^[6] will reject the Agency Order.^[7] Members may use PRIME to execute complex orders at a net price. “cPRIME” is the process by which a Member may electronically submit a “cPRIME Order” (as defined in Rule 518(b)(7)) it represents as agent (a “cPRIME Agency Order”) against principal or solicited interest for execution (a “cPRIME Auction”), subject to the criteria enumerated in Policy .12 of Rule 515A.^[8]

Specifically, the Exchange proposes to amend Exchange Rule 515A(a)(2)(i)(B) related to Request for Response (“RFR”) messages for PRIME and cPRIME Auctions. The Exchange proposes to amend the information displayed in an RFR message. Currently, the RFR details the option, side, size, and initiating price through the Exchange's Administrative Information Subscriber data feed.^[9] The Exchange now proposes to remove the initiating price detail from the RFR message so that the RFR message will only disseminate option, side, and size.

The Exchange notes other options exchanges with price improvement auctions do not provide the initiating price in their notification messages.^[10]

Implementation

The Exchange proposes to implement this functionality in Q3 of 2026 and will issue an alert notifying market participants of the exact date.

2. Statutory Basis

The Exchange believes that the proposed rule change is consistent with Section 6(b) of the Act,^[11] in general, and furthers the objectives of Section 6(b)(5) of the Act,^[12] in particular, in that it is designed to prevent fraudulent and manipulative acts and practices, to promote just and equitable principles of trade, to foster cooperation and coordination with persons engaged in regulating, clearing, settling, processing information with respect to, and facilitating transactions in securities, to remove impediments to and perfect the mechanism of a free and open market and a national market system, and, in general, to protect investors and the public interest. The Exchange also believes the proposed rule change is consistent with the Section 6(b)(5) ^[13] requirement that the rules of an exchange not be designed to permit unfair discrimination between customers, issuers, brokers, or dealers.

The Exchange's proposal to remove the price information from the RFR detail is consistent with the Act because it will encourage responders to submit more aggressive prices resulting in greater price improvement. The proposed amendment protects investors and the public interest by introducing competitive uncertainty to the auction process to drive meaningful price improvement and prevent responders from anchoring to the initiating price. The Exchange believes that removing the initiating price from the RFR detail will encourage more competition in ( printed page 51817) PRIME and cPRIME Auctions and result in greater opportunities for potential price improvement.

B. Self-Regulatory Organization's Statement on Burden on Competition

The Exchange does not believe that the proposed rule change will impose any burden on competition that is not necessary or appropriate in furtherance of the purposes of the Act.

The proposed change will not impose any burden on intramarket competition because the same RFR message will be disseminated to all market participants.

The Exchange does not believe the proposed rule change will impose any burden on intermarket competition that is not necessary or appropriate in furtherance of the purposes of the Act because it relates to orders submitted into the PRIME or cPRIME Auction mechanism on the Exchange. Additionally, the Exchange notes that the rules of at least one other options exchange with a price improvement auction does not broadcast price.^[14] The Exchange believes the proposed rule benefits competition as other exchanges may make similar changes to their rules.

For all the reasons stated, the Exchange does not believe that the proposed rule change will impose any burden on competition not necessary or appropriate in furtherance of the purposes of the Act, and believes the proposed rule change will enhance competition.

C. Self-Regulatory Organization's Statement on Comments on the Proposed Rule Change Received From Members, Participants, or Others

Written comments were neither solicited nor received.

III. Date of Effectiveness of the Proposed Rule Change and Timing for Commission Action

Because the foregoing proposed rule change does not (i) significantly affect the protection of investors or the public interest; (ii) impose any significant burden on competition; and (iii) become operative for 30 days after the date of the filing, or such shorter time as the Commission may designate, it has become effective pursuant to Section 19(b)(3)(A)(iii) of the Act ^[15] and subparagraph (f)(6) of Rule 19b-4 thereunder.^[16]

A proposed rule change filed under Rule 19b-4(f)(6) ^[17] normally does not become operative prior to 30 days after the date of the filing. However, pursuant to Rule 19b-4(f)(6)(iii),^[18] the Commission may designate a shorter time if such action is consistent with the protection of investors and the public interest. The Exchange requests that the Commission waive the 30-day operative delay so that the proposed rule change may become operative immediately upon filing. The Exchange states that a waiver will permit the Exchange to immediately amend its PRIME and cPRIME functionality to remove the price detail from its RFR message, similar to other option exchanges' notification messages for price improvement auctions.^[19] The Exchange believes that permitting the Exchange to remove the price detail in a more expeditious manner will improve execution quality by enhancing competitive dynamics to the benefit of market participants by eliciting the best possible prices through competitive responses. For these reasons, and because the proposal raises no new or novel legal or regulatory issues, the Commission finds that waiver of the 30-day operative delay is consistent with the protection of investors and the public interest. Accordingly, the Commission waives the 30-day operative delay and designates the proposed rule change to be operative upon filing.^[20]

At any time within 60 days of the filing of the proposed rule change, the Commission summarily may temporarily suspend such rule change if it appears to the Commission that such action is necessary or appropriate in the public interest, for the protection of investors, or otherwise in furtherance of the purposes of the Act. If the Commission takes such action, the Commission shall institute proceedings to determine whether the proposed rule should be approved or disapproved.

IV. Solicitation of Comments

Interested persons are invited to submit written data, views, and arguments concerning the foregoing, including whether the proposed rule change is consistent with the Act. Comments may be submitted by any of the following methods:

Electronic Comments

• Use the Commission's internet comment form (www.sec.gov/​rules/​sro.shtml). or
• Send an email torule-comments@sec.gov. Please include file number SR- MIAX-2026-31 on the subject line.

Paper Comments

• Send paper comments in triplicate to Secretary, Securities and Exchange Commission, 100 F Street NE, Washington, DC 20549-1090.

All submissions should refer to file number SR-MIAX-2026-31. This file number should be included on the subject line if email is used. To help the Commission process and review your comments more efficiently, please use only one method. The Commission will post all comments on the Commission's internet website ( www.sec.gov/​rules/​sro.shtml). Copies of the filing also will be available for inspection and copying at the principal office of the Exchange. Do not include personal identifiable information in submissions; you should submit only information that you wish to make available publicly. We may redact in part or withhold entirely from publication submitted material that is obscene or subject to copyright protection. All submissions should refer to file number SR-MIAX-2026-31 and should be submitted on or before September 1, 2026.