Pursuant to Section 19(b)(1) ^[1] of the Securities Exchange Act of 1934 (“Act”) ^[2] and Rule 19b-4 thereunder,^[3] notice is hereby given that, on September 23, 2026, the Investors Exchange LLC (“IEX” or “Exchange”) filed with the Securities and Exchange Commission (“Commission”) the proposed rule change as described in Items I, II and III below, which Items have been prepared by the self-regulatory organization. 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

Pursuant to the provisions of Section 19(b)(1) under the Act,^[4] and Rule 19b-4 thereunder,^[5] the Exchange is filing with the Commission a proposed rule change to amend Supplementary Material .04 and .05 to IEX Rule 23.150(h) to change three of the variables in the Options Risk Parameter quote instability calculation, each within the permitted ranges specified therein. The Exchange has designated this proposal as constituting an interpretation with respect to the administration of an existing IEX Rule pursuant to Rule 19b-4(f)(1) under the Act.^[6]

The text of the proposed rule change is available at the Exchange's website at www.iexexchange.io/​resources/​regulation/​rule-filings and at the principal office of the Exchange.

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

In its filing with the Commission, the self-regulatory organization 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 self-regulatory organization 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 the Statutory Basis for, the Proposed Rule Change

1. Purpose

On September 18, 2025, the Commission approved IEX's rule change proposal to adopt rules governing the trading of options on the Exchange in a new facility called “IEX Options”; ^[7] IEX Options has announced its plan to commence trading options on October 2, 2026.^[8] The purpose of the proposed rule change is to amend Supplementary Materials .04 and .05 to IEX Rule 23.150(h) to change three of the variables in the Options Risk Parameter quote instability calculation, each within the range specified therein. Pursuant to IEX Rule 23.150(h), IEX Options will offer Market Makers the Options Risk Parameter (“ORP”), which the Market Makers can elect to apply to a quotation that rests on the Order Book at the price designated by the Market Maker that entered the quotation.^[9] When the ORP is triggered based on pre-defined criteria in IEX rules, the relevant quotation(s) will be adjusted or canceled in the manner specified in IEX rules.^[10]

As described in the Options Rule Filing, the ORP will leverage IEX's proprietary mathematical formula—the Options Quote Indicator, which is a fixed formula specified transparently in IEX's rules, to assess the materiality of an imminent change to the current best Protected Bid ^[11] of the Away Markets ^[12] to a lower price or of an imminent change to the current best Protected Offer ^[13] of the Away Markets to a higher price for a particular listed options series ( i.e., an imminent adverse price change).^[14] The Indicator utilizes real time relative quoting activity of protected quotations from Signal Exchanges (as defined in IEX Rule 11.190(g)) in securities underlying each listed options series and a proprietary mathematical calculation (the “quote instability calculation”), as described in more detail below, to assess the impact of a price change in the underlying on the price of a particular options series.^[15] When the quote instability calculation identifies an imminent adverse price change in a particular listed options series, it will generate a quote instability determination.^[16] If a Market Maker has elected that its quotations be subject to the ORP, and a quote instability determination is generated for an options series quoted by a Market Maker and the quote is above (below) the price level of the quote instability determination, the quote will be either cancelled or repriced to the price level of the quote instability determination, as instructed by the Market Maker.^[17]

Supplementary Materials .04 and .05 to IEX Rule 23.150(h) provide that the Exchange may change three of the variables in the ORP quote instability calculation. For two aspects of the Quote Instability Calculation formula—the Delta Bound Band ^[18] and the Quote Instability Threshold ^[19] — Supplementary Material .04 to IEX Rule 23.150(h) specifies the possible range of values the Exchange may use for each aspect and the initial value for each aspect. Similarly, for the frequency of calculation of implied volatility, which is used to calculate Delta, Supplementary Material .05 to IEX Rule 23.150(h) specifies that it will be calculated each half-hour of System operation but that the Exchange may determine to calculate the value more frequently based on its assessment of factors that would optimize application of the ORP.^[20]

As specified in Supplementary Material .04 and .05 to IEX Rule 23.150(h), in the event that the Exchange determines to change any of the two variables described above or the frequency of its calculation of implied volatility, it will submit a rule filing pursuant to Rule 19b-4(f) specifying the new value(s). Furthermore, as specified in the Options Rule Filing (and consistent with its approval by the Commission), if the Exchange determines to change such values within the applicable specified ranges, the Exchange will submit a rule filing pursuant to Rule 19b-4(f)(1) under the Act ^[21] (or other appropriate rule filing type) specifying the new value, within the range of possible values specified in the applicable rule. IEX believes that the proposed changes in this rule filing to values that fall within the previously approved range of possible values constitutes a stated policy, practice, or interpretation with respect to the meaning, administration, or enforcement of an existing rule, and therefore that a filing pursuant to Rule 19b-4(f)(1) under the Exchange Act is appropriate.^[22]

In preparation for launch of IEX Options, the Exchange proposes to modify each of these three (Delta Bound Band, Quote Instability Threshold, and ( printed page 63608) Implied Volatility calculation frequency) variables, as set forth below, in order to optimize the application of the ORP for launch with more conservative settings than initially approved (but within the approved ranges), in order to enable market participants to acclimate to IEX's new options market. The proposed rule change would be operative for IEX Options launch, currently scheduled to begin on October 2, 2026.

Accordingly, IEX proposes to amend Supplementary Material .04 and .05 to IEX Rule 23.150(h) to reflect such modifications to the value of each of the three variables, as described above.

The Exchange will issue a Trading Alert announcing the modifications to the values of the three variables, as described above, upon effectiveness of this proposed rule change.

2. Statutory Basis

IEX believes that the proposed rule change is consistent with Section 6(b) ^[23] of the Act in general, and furthers the objectives of Section 6(b)(5) of the Act,^[24] 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 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. Specifically, as discussed in the Purpose section, the proposed change constitutes a stated policy, practice or interpretation with respect to the meaning, administration, or enforcement of existing IEX rules as contemplated by the Options Rule Filing. In this regard, IEX believes that the changes to the manner in which IEX will administer the ORP will optimize application of the ORP for IEX Options launch and thereby support Market Makers in providing more competitive quotes which will benefit all market participants and thereby support the protection of investors and the public interest.

Additionally, the Exchange notes that the ORP will continue to leverage a fixed formula specified transparently in IEX rules, that was previously approved by the Commission.^[25] The Exchange is not proposing to add any new functionality, but merely to adjust the values for the three variables for the ORP quote instability calculation within the ranges set forth in IEX rules, as discussed in the Purpose section. Thus, IEX does not believe that the proposed rule change raises any new or novel issues that have not already been considered by the Commission, in that the ORP functionality and IEX's ability to change the three values within specified ranges were previously approved by the Commission.^[26]

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

IEX does not believe that the proposed rule change will result in any burden on competition that is not necessary or appropriate in furtherance of the purposes of the Act. To the contrary, as discussed in the Statutory Basis section, the proposal is designed to enhance competition by optimizing application of the ORP for IEX Options launch.

The Exchange does not believe that the proposed rule change will impose any burden on intra-market competition because it will apply to all Options Members in the same manner and any Options Member could become a Market Maker subject to meeting applicable requirements.

The Exchange also does not believe that the proposal will impose any burden on inter-market competition that is not necessary or appropriate. Competing exchanges are free to adopt similar functionality, subject to the Commission rule filing process.

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

The foregoing rule change has become effective pursuant to Section 19(b)(3)(A)(i) ^[27] of the Act and Rule 19b-4(f)(1) ^[28] thereunder, in that the proposed rule change constitutes a stated policy, practice, or interpretation with respect to the meaning, administration, or enforcement of an existing rule of IEX.

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 under Section 19(b)(2)(B) ^[29] of the Act to determine whether the proposed rule change 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-IEX-2026-36 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-IEX-2026-36. 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/​ ( printed page 63609) rules/​sro.shtml ). Copies of the filing 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-IEX-2026-36 and should be submitted on or before October 27, 2026.