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Notice2026-18662

Self-Regulatory Organizations; MEMX LLC; Notice of Filing and Immediate Effectiveness of a Proposed Rule Change To Amend Its Rules To Permit Trading 23 Hours per Day, Five Days per Week

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Published
September 14, 2026

Issuing agencies

Securities and Exchange Commission

Full Text

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<title>Federal Register, Volume 91 Issue 176 (Monday, September 14, 2026)</title>
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[Federal Register Volume 91, Number 176 (Monday, September 14, 2026)]
[Notices]
[Pages 58185-58193]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-18662]


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SECURITIES AND EXCHANGE COMMISSION

[Release No. 34-106310; File No. SR-MEMX-2026-28]


Self-Regulatory Organizations; MEMX LLC; Notice of Filing and 
Immediate Effectiveness of a Proposed Rule Change To Amend Its Rules To 
Permit Trading 23 Hours per Day, Five Days per Week

September 9, 2026.
    Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934 
(the ``Act''),\1\ and Rule 19b-4 thereunder,\2\ notice is hereby given 
that on August 28, 2026, MEMX LLC (``MEMX'' or the ``Exchange'') filed 
with the Securities and Exchange Commission (the ``Commission'') the 
proposed rule change as described in Items I, II, and III below, which 
Items have been prepared by the Exchange. The Exchange filed the 
proposal as a ``non-controversial'' proposed rule change pursuant to 
Section 19(b)(3)(A)(iii) of the Act \3\ and Rule 19b-4(f)(6) 
thereunder.\4\ The Commission is publishing this notice to solicit 
comments on the proposed rule change from interested persons.
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    \1\ 15 U.S.C. 78s(b)(1).
    \2\ 17 CFR 240.19b-4.
    \3\ 15 U.S.C. 78s(b)(3)(A).
    \4\ 17 CFR 240.19b-4.
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I. Self-Regulatory Organization's Statement of the Terms of Substance 
of the Proposed Rule Change

    The Exchange is filing with the Commission a proposed rule change 
to amend its rules to permit the trading of equity securities and UTP 
Exchange Traded Products on the Exchange 23 hours per day, five days 
per week. The text of the proposed rule change is provided in Exhibit 5 
and is available on the Exchange's website at <a href="https://info.memxtrading.com/regulation/rules-and-filings/">https://info.memxtrading.com/regulation/rules-and-filings/</a>.

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

[[Page 58186]]

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 its rules to permit the trading of 
equity securities and UTP Exchange Traded Products on the Exchange 23 
hours per day, five days per week (``23x5 Trading''). The proposal is 
based substantially on a proposal submitted by Cboe EDGX Exchange, Inc. 
(``EDGX'') that was recently approved by the Commission.\5\ Further, 
the Commission has approved other exchanges to offer 23x5 Trading, 
although none have begun to do so.\6\
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    \5\ See Securities Exchange Act Release No. 105587 (May 29, 
2026); 91 FR 33238 (June 3, 2026) (SR-CboeEDGX-2026-19) (Notice of 
Filing of Amendment No. 1 and Order Granting Accelerated Approval of 
a Proposed Rule Change, as Amended by Amendment No. 1, To Extend the 
Exchange's Trading Hours to 23 Hours per Day, Five Days per Week) 
(``EDGX Approval Order''). While certain of the Exchange's rules 
differ due to the Exchange's lack of order queuing functionality, 
order types and modifiers, and the Exchange's lack of a formal 
opening process like EDGX, the basis for the proposal is materially 
similar, and the specific sessions offered under this proposal are 
identical to EDGX. As such, this filing does not raise any novel or 
unique issues not previously considered by the Commission.
    \6\ See Securities Exchange Act Release No. 105532 (May 21, 
2026); 91 FR 31509 (May 27, 2026) (SR-NYSEArca-2026-53) (Notice of 
Filing of Filing and Immediate Effectiveness of Proposed Rule Change 
To Amend Temporary Rule 7.34-E(T) To Provide for an Overnight 
Trading Session and To Amend the Hours for the Exchange's Early 
Trading Session and the Late Trading Session, and To Make 
Corresponding Changes to Other Rules); Securities Exchange Act 
Release No. 890235 [sic] (November 27, 2024); 89 FR 97072 [sic] 
(Order Approving Application of 24X National Exchange, LLC for 
registration as a national securities exchange and to trade 23 hours 
per day, 5 days per week) (``24X Approval Order''); Securities 
Exchange Act Release No. 105199 (April 10, 2026); 91 FR 20222 (April 
15, 2026) (SR-Nasdaq-2025-109) (Notice of Filing of Amendment Nos. 2 
and 3 and Order Granting Accelerated Approval of a Proposed Rule 
Change, as Amended by Amendment Nos 2 and 3, To Extend the 
Exchanges' Trading Hours to 23 Hours a Day, Five Days a Week) 
(``Nasdaq Approval Order'').
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Background
    The latest change to impact the markets is rising investor interest 
in trading U.S. equities during overnight hours, especially among 
investors located outside of the United States. To align MEMX with 
emerging investor interest in trading outside of traditional U.S. 
Market hours, the Exchange proposes to extend its hours for trading to 
23 hours per day, 5 days per week. The Exchange believes that 23x5 
Trading will benefit investors and the national market system by 
increasing market accessibility, promoting capital formation, and 
facilitating portfolio management.
    Currently, Users \7\ may enter orders into the System \8\ from 4:00 
a.m. to 8:00 p.m. Eastern Time (``ET'').\9\ The Exchange offers three 
trading sessions on each day it is open for trading: (1) the Pre-Market 
Session \10\ (4:00 a.m. to 9:30 a.m.); (2) Regular Trading Hours \11\ 
(9:30 a.m. to 4:00 p.m.); and (3) the Post-Market Session \12\ (4:00 
p.m. to 8:00 p.m.). During each session, orders may be entered, 
executed, or routed away.\13\ The Exchange does not offer queueing 
functionality, and as such, it does not accept orders prior to any 
trading session, however, it only accepts certain order types during 
specific sessions. For example, Market Orders \14\ are only eligible 
for execution by the System during the Market Session,\15\ and not 
during the Pre-Market or Post-Market Sessions.
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    \7\ The term ``User'' shall mean any Member or Sponsored 
Participant who is authorized to obtain access to the System 
pursuant to Rule 11.3[sic] See Rule 1.5(jj).
    \8\ The term ``System'' shall mean the electronic communications 
and trading facility designated by the Board through which 
securities orders of Users are consolidated for ranking, execution 
and, when applicable, routing. See Rule 1.5(gg).
    \9\ See Rule 11.1(a). All times stated herein are in ET.
    \10\ See Rule 1.5(x).
    \11\ See Rule 1.5(bb). ``Regular Trading Hours'' is also 
referred to in the Exchange's rules as the ``Market Session'' which 
is defined in Rule 1.5(o).
    \12\ See Rule 1.5(w).
    \13\ See Rule 11.1(a).
    \14\ ``Market Orders'' are orders to buy or sell a stated amount 
of a security that is to be executed at the NBBO or better when the 
order reaches the Exchange. See Rule 11.8(a).
    \15\ See Rule 11.8(a)(4).
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    To accommodate 23x5 Trading, the Exchange proposes to introduce a 
new Overnight Trading Session, along with conforming amendments to its 
session-specific order handling rules, as described below.
Proposal
    The Exchange proposes to amend its rules to enable 23x5 Trading by 
adopting a new Overnight Trading Session.
Definitions
    The Exchange proposes to amend and adopt certain definitions 
provided in Exchange Rule 1.5.
    First, the Exchange proposes to adopt the new defined term, 
``Overnight Trading Session.'' As proposed, the Overnight Trading 
Session shall mean the time between 9:00 p.m. on any night preceding a 
business day \16\ and 4:00 a.m. on the following calendar day. Rather 
than defining the Overnight Trading Session by reference to specific 
calendar days of the week (e.g., Sunday through Thursday), the proposed 
definition is anchored to the concept of a ``night preceding a business 
day.'' This approach provides that the Overnight Trading Session is 
triggered by the existence of an upcoming trading day rather than by 
enumeration of calendar days, providing a more durable and flexible 
framework that accommodates changes to the Exchange's trading calendar 
(including holidays and other non-business days) without requiring 
conforming amendments to the session definition itself. For example, 
when a holiday falls on a Monday, there is no night preceding a 
business day on the prior Sunday and therefore no Overnight Trading 
Session will commence that Sunday evening, consistent with the 
Exchange's proposed holiday schedule under Rule 11.1(b). As discussed 
further below under ``Contingency on Industry Readiness,'' the Exchange 
shall not commence operation of the Overnight Trading Session until 
specified Equity Data Plan readiness conditions have been satisfied. 
The proposed term would provide ``Overnight Trading Session'' shall 
mean the time between 9:00 p.m. on any night preceding a business day, 
as provided in Rule 11.1(b), and 4:00 a.m. Eastern Time on the 
following calendar day. For the avoidance of doubt, notwithstanding 
anything to the contrary in these Rules, the Exchange shall not 
commence operation of the Overnight Trading Session unless the Equity 
Data Plans (1) have established a mechanism to collect, consolidate, 
process and disseminate quotation and transaction information at all 
times during the Overnight Trading Session that is equivalent to the 
mechanism established for Exchange trading hours during Regular Trading 
Hours, and (2) have provided the Exchange with notification that they 
are prepared to collect, consolidate, process and disseminate quotation 
and transaction information to accommodate the Overnight Trading 
Session. Prior to commencing operation during the

[[Page 58187]]

Overnight Trading Session, the Exchange will file a proposed rule 
change pursuant to Section 19(b) of the Exchange Act and the rules 
thereunder to amend its rules confirming that the Exchange is able to 
comply with its obligations under the Exchange Act and the rules 
thereunder during the Overnight Trading Session and that such Equity 
Data Plans are prepared to collect, consolidate, process and 
disseminate quotation and transaction information at all times during 
the Overnight Trading Session (``Overnight Trading Session Proposed 
Rule Change''). If the Overnight Trading Session Proposed Rule Change 
is not filed within 18 months of the effectiveness of this proposed 
rule change, the Exchange will promptly file a proposed rule change to 
remove the rules that apply to the Overnight Trading Session.
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    \16\ See proposed Rule 11.1(b). A business day is any day the 
Exchange is open for trading, which includes any Monday, Tuesday, 
Wednesday, Thursday, and Friday, other than a holiday.
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    Second, proposed Rule 1.5(i) would define ``Equity Data Plans'' to 
mean the effective national market system plan(s) governing the 
collection, consolidation, processing, and dissemination of 
consolidated equity market data via the exclusive securities 
information processors (``SIPs''), including: (1) the Consolidated Tape 
Association Plan (``CTA Plan''); (2) the Consolidated Quotation Plan 
(``CQ Plan''); (3) the Joint Self-Regulatory Organization Plan 
Governing the Collection, Consolidation and Dissemination of Quotation 
and Transaction Information for Nasdaq-Listed Securities Traded on 
Exchanges on an Unlisted Trading Privileges Basis (``UTP Plan''); (4) 
the CT Plan established by the Limited Liability Company Agreement of 
CT Plan LLC; and (5) any successor to the named Plan(s).
Trading Rules
    The Exchange proposes to amend Rules 11.1 (Hours of Trading and 
Trading Days), 11.6 (Definitions), 11.8 (Order Types and Modifiers), 
11.10 (Order Execution), 11.15 (Clearly Erroneous Executions), 11.22 
(Limit Up-Limit Down Plan and Trading Halts on the Exchange), and to 
adopt Rule 11.24 (Weekday Trading Pauses) to reflect necessary updates 
to provide for 23x5 trading functionality.
a. Rule 11.1--Hours of Trading and Trading Days
    The Exchange proposes to amend Rule 11.1(a) to add reference to the 
Overnight Trading Session, and to adopt Rule 11.1(a)(1) to establish 
session eligibility framework to accommodate 23x5 Trading. Under 
current Rule 11.1(a), orders may be entered, canceled, modified, 
executed on, or routed away from the Exchange during the Pre-Market 
Session, the Market Session,\17\ and the Post-Market Session. The 
current rule also provides that all orders are eligible for execution 
during the Market Session, and that orders may be entered into the 
System during Exchange Operating Hours (from 4:00 a.m. until 8:00 p.m. 
Eastern Time).
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    \17\ See supra note 11.
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    The Exchange proposes to add the Overnight Trading Session to the 
list of sessions in which orders may be entered, canceled, modified, 
executed on or routed away from the Exchange, and indicate that orders 
may be entered into the System starting at 9:00 p.m. Eastern Time on 
any day preceding a business day, as provided in Rule 11.1(b), until 
8:00 p.m. Eastern Time on the same trading day.\18\
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    \18\ A ``trading day'' refers to the 23-hour period commencing 
at 9:00 p.m. ET on one calendar day and ending at 8:00 p.m. ET on 
the next calendar day for the period from Sunday at 9:00 p.m. ET 
through Friday at 8:00 p.m. ET.
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    Proposed Rule 11.1(a)(1) would provide that an order is eligible to 
participate in the designated trading session(s) only and may remain in 
effect for one or more consecutive trading sessions on a particular 
day. An order designated for a session that has not yet begun or has 
already ended will be rejected. An order entered without a trading 
session designation will default to a Day \19\ order, making it 
eligible to participate from the Overnight Trading Session through the 
end of Regular Trading Hours.
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    \19\ A ``Day'' order is defined under the proposed amended Rule 
11.6(o)(2) as an instruction the User may attach to an order stating 
that an order to buy or sell starting with the Overnight Trading 
Session and, if not executed, expires at the end of Regular Trading 
Hours.
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    The Exchange also proposes to amend Rule 11.1(b) to define 
``business day'' and to specify the days on which the Exchange will be 
open for trading under the proposed 23x5 framework. A business day is 
any day the Exchange is open for trading, which includes any Monday, 
Tuesday, Wednesday, Thursday, and Friday, other than a holiday listed 
below. The Exchange will not be open for business on the following 
holidays: New Year's Day, Dr. Martin Luther King Jr. Day, Presidents' 
Day, Good Friday, Memorial Day, Juneteenth National Independence Day, 
Independence Day, Labor Day, Thanksgiving Day, and Christmas Day. When 
a holiday falls on a Saturday, the Exchange will not be open for 
business on the preceding Friday. When a holiday falls on a Sunday, the 
Exchange will not be open for business on the following Monday, unless 
otherwise indicated by the Exchange. On days when the Exchange closes 
early (``Early Market Close''), Regular Trading Hours will be from 9:30 
a.m. to 1:00 p.m. and the Post-Market Session will be from 1:00 p.m. to 
5:00 p.m. Trading shall resume with the Overnight Trading Session on 
any night preceding a business day. The Exchange also proposes to amend 
Rule 11.1(b) to provide that the Exchange will be open for the 
transaction of business on each business day, including the Overnight 
Trading Session on the preceding calendar day.
    Under the proposed 23x5 framework, the trading day will be 
structured as follows. The Overnight Trading Session will run from 9:00 
p.m. to 4:00 a.m., followed by the Pre-Market Session from 4:00 a.m. to 
9:30 a.m., Regular Trading Hours from 9:30 a.m. to 4:00 p.m., and the 
Post-Market Session from 4:00 p.m. to 8:00 p.m. Between 8:00 p.m. and 
9:00 p.m. each weekday, the Exchange will pause trading to conduct 
maintenance, testing, and processing of corporate actions (such as 
mergers, stock splits, and dividends) that become effective the 
following trading day.\20\ This pause also provides market participants 
with time to process and clear trades before the start of a new trading 
day. For dates on which the Exchange is not open for business under 
Rule 11.1(b), the market closure will be effective at 8:00 p.m. on the 
calendar day preceding the closure date. For Early Market Close 
days,\21\ the closure will instead be effective at 5:00 p.m. on the 
calendar day preceding the closure date. In either case, the Exchange 
will re-open at 9:00 p.m. on the closure date, unless the closure date 
is immediately followed by a non-business day, in which case the 
Exchange will re-open at 9:00 p.m. on the day preceding the next 
business day.
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    \20\ As noted above, these trading sessions are identical to 
those in the EDGX Approval Order, other than the titles given to the 
Pre-Market and Post-Market Sessions, which are known as the Pre-
Opening and Post-Closing Sessions on EDGX.
    \21\ Regular trading hours for days when the market closes early 
are typically 9:30 a.m. to 1:00 p.m. See e.g., Thanksgiving Early 
Close and Christmas Early Close at: <a href="https://info.memxtrading.com/market-hours-and-holiday-schedule/">https://info.memxtrading.com/market-hours-and-holiday-schedule/</a>[sic]
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b. Rule 11.6(o)--Time-In-Force ``TIF'' Instructions
    The Exchange does not propose any changes to its existing TIF 
instructions in connection with the Overnight Trading Session, with two 
exceptions described below. The Exchange believes the existing TIF 
framework otherwise accommodates the proposed 23x5 structure without 
modification.
    The Exchange proposes a conforming amendment to the Day order TIF

[[Page 58188]]

definition to permit acceptance of Day Orders during the Overnight 
Trading Session. Under the current definition, a Day Order entered 
``into the System before the opening for business on the Exchange as 
determined pursuant to Rule 11.1, or after the closing of Regular 
Trading Hours'' is rejected. Because the Overnight Trading Session 
commences at 9:00 p.m. the current definition would, as written, result 
in the rejection of Day Orders entered during the Overnight Trading 
Session. This outcome is inconsistent with the proposed 23x5 framework, 
under which Day Orders should be eligible for entry beginning at the 
Overnight Trading Session and should remain eligible for execution 
throughout the Overnight Trading Session, Pre-Market Session, and 
Regular Trading Hours. Accordingly, the Exchange proposes to amend the 
Day order TIF definition to provide that a Day Order entered during the 
Overnight Trading Session will be accepted by the Exchange and, if not 
executed, will expire at the end of Regular Trading Hours on the same 
trading day. For added clarity, the Exchange also proposes to add that 
any Day Order entered into the System during the Post-Market Session or 
before the opening for business on the Exchange as determined pursuant 
to Rule 11.1 will be rejected.
    This amendment is limited to conforming the Day order definition to 
the expanded order entry window introduced by the proposed 23x5 
framework and does not alter any other aspect of the Day order TIF 
instruction. For the avoidance of doubt, orders will expire on the 
trading day for which they are entered; as described above, a trading 
day is deemed to begin at 9:00 p.m. Eastern Time on the preceding 
calendar day. As amended, a Day Order entered at 9:00 p.m. on a day 
preceding a business day will remain eligible for execution throughout 
the Overnight Trading Session, Pre-Market Session, and Regular Trading 
Hours on that business day, expiring at 4:00 p.m. Eastern Time that 
trading day.
    Second, the Exchange is proposing a conforming amendment to the 
definition of the TIF ``Good-'til Time (``GTT'') in order to permit 
acceptance of GTT Orders during the Overnight Trading Session. 
Currently, GTT is a TIF the User may attach to an order specifying the 
time of day at which the order expires, which is designated for 
execution starting with the Pre-Market Session. Any unexecuted portion 
of an order with a TIF instruction of GTT will be cancelled at the 
expiration of the User's specified time, which can be no later than the 
close of the Post-Market Session. At this time, the Exchange proposes 
to replace the reference to the ``Pre-Market Session'' with the 
``Overnight Trading Session'', as the intent of the 23x5 framework is 
to begin the business day with the Overnight Trading Session, rather 
than the Pre-Market Session. This amendment is limited to conforming 
the GTT order definition to the expanded order entry window introduced 
by the proposed 23x5 framework and does not alter any other aspect of 
the GTT order instruction.
c. Rule 11.8--Order Types
    The Exchange proposes two conforming amendments to Rule 11.8 to add 
reference to the Overnight Trading Session in the two order types that 
currently specify session eligibility, Limit Orders \22\ and Pegged 
Orders.\23\ Specifically, both of these order types are currently 
eligible for execution during the Pre-Market Session, Market Session, 
and Post-Market Session, and the Exchange proposes to add the Overnight 
Trading Session to this list in order to ensure that those orders are 
permitted in all offered sessions. However, the Exchange proposes 
additional amendments with respect to Pegged Orders.
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    \22\ See Rule 11.8(b).
    \23\ See Rule 11.8(c).
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    As noted previously, Pegged Orders are currently eligible for 
execution during the Pre-Market Session, Market Session, and Post-
Market Session, and per Rule 11.6(h)(1) and (2), a User may, but is not 
required to, include a limit price on Pegged Orders. The Exchange is 
now proposing to amend Rule 11.8(c)(4) to require that any Pegged 
Orders entered outside of Regular Trading Hours must be entered with a 
limit price. Specifically, the Exchange's proposed text indicates all 
Pegged Orders may be entered during the Market Session, and only Pegged 
Orders with a limit price may be entered during the Overnight Trading 
Session, Pre-Market Session, and the Post-Market Session.\24\ As a 
result of this change, Pegged Orders entered without a limit price will 
be rejected during the Overnight Trading Session, Pre-Market Session, 
and Post-Market Session. The Exchange wishes to make this change given 
that Pegged Orders without limit prices represent heightened execution 
risk in extended hours sessions where liquidity conditions may differ 
materially from those present during Regular Trading Hours and where 
the NBBO may be wider or less reliable. Without a limit price to 
constrain the execution price, a Pegged Order could execute at a price 
that is disadvantageous to the submitting party in a manner that is 
less likely to occur during Regular Trading Hours, due to the potential 
lack of liquidity and less reliable NBBO. The Exchange notes that this 
amendment is consistent with EDGX, where orders without a limit price 
are similarly prevented from executing outside of Regular Trading 
Hours.
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    \24\ The Exchange is proposing to delete the word ``executed'' 
in this provision (Rule 11.8(c)(4)), and replace it with the word 
``entered'' for the purpose of added clarity.
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d. Rule 11.10--Order Execution
    The Exchange proposes a conforming amendment to Rule 11.10 to 
reference the Overnight Trading Session in the provision governing 
compliance with Regulation NMS. As amended, for any execution to occur 
during the Overnight Trading Session, Pre-Market Session, or Post-
Market Session, the price must be equal to or better than the highest 
bid or lowest offer in the MEMX Book or as disseminated by the 
responsible single plan processor, unless the order is marked ISO or a 
Protected Bid is crossing a Protected Offer. This amendment is non-
substantive and preserves the existing execution standard applicable 
outside of Regular Trading Hours.
    Additionally, to support 23x5 trading, the Exchange will offer 
Members a risk control under Rule 11.10, Interpretation and Policy 
.01(c) that would prohibit orders from executing during the Overnight 
Trading Session. The Exchange plans to offer this new control as one of 
the controls available to Members under this provision, which permits 
the Exchange to offer ``controls related to the order types or 
modifiers that can be utilized (including pre-market, post-market, 
short sales and ISOs)''. Accordingly, the Exchange proposes to add the 
word ``overnight'' to the parenthetical in Rule 11.10, Interpretation 
and Policy .01(c).\25\
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    \25\ The Exchange is also proposing a non-substantive amendment 
to Rule 11.10, Interpretation and Policy .01(c) to correct a 
typographical error, adding an inadvertently omitted hyphen in 
``pre-market''.
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e. Rule 11.15--Clearly Erroneous Executions
    The Exchange proposes conforming amendments to Rule 11.15 to add 
references to the Overnight Trading Session throughout the clearly 
erroneous execution framework. These amendments appear in the 
provisions governing review of transactions occurring outside of 
Regular Trading Hours, including the numerical guidelines table, the 
Multi-Stock Event

[[Page 58189]]

provisions, the additional factors provision, the Outlier Transaction 
provision, the Reference Price provision, and the Officer Acting On Own 
Motion provision. In each case, the amendment adds ``Overnight Trading 
Session'' alongside ``Pre-Market Session'' and ``Post-Market Session'' 
without altering the substantive standards or procedures applicable to 
clearly erroneous execution reviews. The Exchange notes that the 
numerical guidelines applicable to the Overnight Trading Session, Pre-
Market Session, and Post-Market Session will remain the same as those 
currently applicable to the Pre-Market Session, and Post-Market 
Session, reflecting the Exchange's view that the same heightened 
thresholds appropriate for extended hours trading remain appropriate 
for the Overnight Trading Session.
f. Rule 11.24--Weekday Trading Pause
    The Exchange proposes to adopt new Rule 11.24 to govern the daily 
trading pause that will occur between the close of the Post-Market 
Session and the commencement of the Overnight Trading Session on each 
weekday. As proposed, the Exchange will pause trading at the conclusion 
of the Post-Market Session at 8:00 p.m. and resume trading with the 
commencement of the Overnight Trading Session at 9:00 p.m. on the day 
preceding the next business day. This one-hour pause is intended to 
provide the Exchange with time to conduct necessary maintenance and 
testing, and to process corporate actions, such as mergers, stock 
splits, and dividends, that become effective the following trading day.
    The pause also provides market participants with time to process 
and clear trades before the start of a new trading day. Proposed Rule 
11.24(a)(1) provides that all orders outstanding on the MEMX Book as of 
8:00 p.m. at the end of the Post-Market Session will be cancelled. The 
Exchange believes it is appropriate to cancel all resting orders at the 
close of the Post-Market Session each weekday to ensure that orders are 
not carried over into the next trading day without an explicit order 
instruction by a Member. This approach provides Members with a clean 
start to each trading day and reduces the risk of unintended executions 
based on stale order instructions.
    Proposed Rule 11.24(a)(2) provides that the Exchange will begin 
accepting orders again at the commencement of the Overnight Trading 
Session at 9:00 p.m. Eastern Time and continue until 8:00 p.m. the 
following calendar day, provided the next calendar day is not a holiday 
or a Friday. Proposed Rule 11.24(a)(2) also provides that trades 
occurring at or after the commencement of the Overnight Trading Session 
at 9:00 p.m. will be assigned a trade date of the following day, 
reflecting that the Overnight Trading Session economically belongs to 
the next trading day even though it commences the prior evening.
Unlisted Trading Privileges
    The Exchange proposes conforming amendments to Rule 11.22 to insert 
references to the Overnight Trading Session with the Pre-Market 
Session. These amendments are non-substantive and are intended solely 
to conform the unlisted trading privileges framework to the proposed 
23x5 session structure by updating the applicable session nomenclature 
and hours.
Risk Disclosures
    The Exchange proposes to adopt new Rule 3.21(h) to establish 
tailored customer disclosure obligations specific to the Overnight 
Trading Session and Pre-Market Session. The existing customer 
disclosure framework under Rule 3.21 requires Members to disclose the 
material trading risks associated with extended hours trading prior to 
accepting an order for execution in those sessions.\26\ The Exchange 
believes that the unique characteristics of the Overnight Trading 
Session and Pre-Market Session (including the hours during which they 
operate, the market conditions that may be present, and the novel 
nature of overnight exchange trading) warrant additional disclosures 
beyond those currently required for other extended hours sessions. 
Proposed Rule 3.21(h) sets forth seven categories of risks that Members 
must disclose to customers in connection with trading during the 
Overnight Trading Session and Pre-Market Session.
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    \26\ The Exchange is proposing to make a minor, non-substantive 
amendment to Rule 3.21 to change ``UTP Derivative Securities as 
defined in Rule 14.1(c)'' to ``UTP Exchange Traded Products as 
defined in Rule 1.5(kk)''.
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    First, proposed Rule 3.21(h)(1) addresses the risk of trading 
during hours in which primary listing markets may not be open. Unlike 
the Post-Market Session, which occurs in close proximity to Regular 
Trading Hours, the Overnight Trading Session and Pre-Market Session 
operate during hours in which primary listing exchanges may not be 
conducting their own trading, regulatory surveillance, or other 
regulatory functions with respect to their listed securities. The 
Exchange believes it is important that customers understand that the 
regulatory infrastructure ordinarily provided by primary listing 
exchanges may not be available during these sessions.
    Second, proposed Rule 3.21(h)(2) addresses the risk that regulatory 
protections available during the Overnight Trading Session and Pre-
Market Session may be more limited or different than those available 
during Regular Trading Hours. For example, certain volatility control 
mechanisms applicable to individual symbols and the broader equities 
market may not be available during the Overnight Trading Session and 
Pre-Market Session. The Exchange believes customers should be informed 
of these potential gaps in regulatory protections before trading during 
these sessions.
    Third, proposed Rule 3.21(h)(3) addresses the risk arising from 
limited trading alternatives during the Overnight Trading Session and 
Pre-Market Session. Because the Exchange may be the only exchange 
trading certain securities during these hours, customers may face 
greater exposure to losses in the event of systems failures or other 
operational issues on the Exchange, as alternative execution venues may 
not be available.
    Fourth, proposed Rule 3.21(h)(4) addresses the risks associated 
with near- continuous trading under the 23x5 framework. With the 
implementation of the Overnight Trading Session, trading on the 
Exchange will occur on a near-continuous basis throughout the week, 
with only limited breaks. This structure may present heightened risks 
related to system maintenance and testing, as well as the pausing and 
resumption of trading, as there will be fewer extended breaks during 
which such activities can be conducted without impacting market 
participants.
    Fifth, proposed Rule 3.21(h)(5) addresses the risk of trading 
during hours in which financial market infrastructure companies are 
closed. Certain important financial market infrastructure providers, 
including other markets, banks, Fedwire Funds Service, and certain 
other providers of settlement services, may be closed during the 
Overnight Trading Session and Pre-Market Session. Trading during hours 
in which the relevant clearing agency and other settlement service 
providers are closed may result in an increased passage of time between 
the execution of a transaction and its final settlement, which may 
expose customers to additional counterparty and settlement risk.
    Sixth, proposed Rule 3.21(h)(6) addresses the risk arising from the 
novel nature of overnight exchange trading. Exchange-facilitated 
trading during overnight hours is a relatively new

[[Page 58190]]

development in the U.S. equities market, and as such, the Overnight 
Trading Session may present unforeseen risks that are not yet fully 
understood or anticipated. The Exchange believes it is appropriate to 
specifically call out the novelty of the Overnight Trading Session so 
that customers can make informed decisions about whether overnight 
trading is appropriate for them.
    Seventh, proposed Rule 3.21(h)(7) provides a general catch-all 
disclosure acknowledging that the Overnight Trading Session and Pre-
Market Session may present additional unforeseen risks beyond those 
specifically enumerated in proposed Rule 3.21(h)(1) through (6). The 
Exchange believes this provision is appropriate given the evolving 
nature of extended hours trading and the potential for market 
conditions or operational circumstances that cannot be fully 
anticipated at this time.
    The Exchange believes that the proposed disclosures under Rule 
3.21(h) are necessary and appropriate to ensure that customers are 
fully informed of the unique risks presented by the Overnight Trading 
Session and Pre-Market Session prior to participating in trading during 
those hours. The proposed disclosures are consistent with the customer 
protection principles underlying the existing Rule 3.21 framework and 
reflect the Exchange's commitment to investor protection in connection 
with the expansion of its trading hours under the proposed 23x5 
framework.
Protections
    The implementation of 23x5 Trading represents an extension of 
trading hours rather than a fundamental restructuring of Exchange 
operations or rules. With the exception of the specific amendments 
discussed above, the Exchange's operational processes, rule text, and 
surveillance programs will continue to apply in the same manner as they 
do today. The following MEMX rules and system features will remain 
unchanged and will apply in full during the Overnight Trading Session: 
Order Types and Order Execution; Membership Rules and Rules of Fair 
Practice; Market Maker Obligations and Priority of Orders; Trading 
Practice Rules and Disciplinary Rules and Enforcement; Clearly 
Erroneous Execution Protections; and Risk Settings.
    With respect to trading halts, the Exchange's existing halt rules 
will apply during the Overnight Trading Session. Consistent with 
current practice during other extended hours sessions, the Exchange 
will halt trading in a security during the Overnight Trading Session to 
the extent required to follow a halt imposed by the primary listing 
exchange for that security. To the extent a security is subject to a 
regulatory halt, news dissemination halt, or other trading pause 
imposed by the primary listing exchange or a national securities 
regulator, the Exchange will halt trading in that security consistent 
with applicable rules and regulatory requirements.
    The Exchange's clearly erroneous execution rules under Rule 11.15 
will apply in full during the Overnight Trading Session, as they 
currently apply during the Pre-Market Session and other extended hours 
sessions. No substantive changes to those rules are proposed in 
connection with this filing. As such, the Exchange's Clearly Erroneous 
rules will continue to mirror those adopted by each national security 
exchange and will continue to ensure that there are consistent 
standards across each exchange for breaking trades, and continuing to 
promote the orderly and efficient operation of the equities markets.
    The Exchange's existing surveillance programs and compliance 
infrastructure will likewise apply fully to trading in the Overnight 
Trading Session. The Exchange currently operates a comprehensive 
regulatory program applicable to the Pre-Market Session, Regular 
Trading Hours, and Post-Market Session, encompassing a suite of 
automated trade surveillance tools, routine Member examinations, and an 
exam-based regulatory program. This regulatory program will extend to 
the Overnight Trading Session without modification, ensuring that 
Members trading during overnight hours are subject to the same level of 
oversight applicable to trading in other sessions. Similarly, the 
Exchange's existing risk settings and controls (including single order 
price and size protections and other fat finger safeguards) will remain 
available and operative during the Overnight Trading Session. The 
Exchange believes that these existing protections, taken together, 
provide a robust framework for managing risk during overnight trading 
that is consistent with the protections available during other extended 
hours sessions.
Contingency on Industry Readiness
    As noted above, the Exchange will not implement its proposed rule 
changes or commence operation of the Overnight Trading Session until 
the Equity Data Plan readiness conditions set forth in proposed Rule 
1.5(i) have been satisfied. Prior to commencing operation of the 
Overnight Trading Session, the Exchange will file a proposed rule 
change pursuant to Section 19(b) of the Exchange Act and the rules 
thereunder confirming that: (i) the Exchange is able to comply with its 
obligations under the Exchange Act and the rules thereunder during the 
Overnight Trading Session; and (ii) the Equity Data Plans are prepared 
to collect, consolidate, process, and disseminate quotation and 
transaction information at all times during the Overnight Trading 
Session. Upon satisfaction of the foregoing conditions, the Exchange 
will announce via Trader Alert the implementation date for its proposed 
rule changes and the go-live date for 23x5 Trading. If the Overnight 
Trading Session Proposed Rule Change is not filed within 18 months of 
the effectiveness of this proposed rule change, the Exchange will 
promptly file a proposed rule change to remove the rules applicable to 
the Overnight Trading Session.
Impact on Fees
    Any impact of the Exchange's 23x5 proposal on its fee schedule will 
be addressed in a subsequent fee filing.
2. Statutory Basis
    The Exchange believes the proposed rule change is consistent with 
the Securities Exchange Act of 1934 (the ``Act'') and the rules and 
regulations thereunder applicable to the Exchange and, in particular, 
the requirements of Section 6(b) of the Act.\27\ Specifically, the 
Exchange believes the proposed rule change is consistent with the 
Section 6(b)(5) \28\ requirements that the rules of an exchange be 
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.
---------------------------------------------------------------------------

    \27\ 15 U.S.C. 78f(b).
    \28\ 15 U.S.C. 78f(b)(5).
---------------------------------------------------------------------------

23x5 Trading Framework
    The Exchange believes the proposed rule change is consistent with 
the Act because it would remove impediments to and perfect the 
mechanism of a free and open market and a national market system by 
providing a rules framework to support 23x5 Trading. As described 
above, the Exchange believes that 23x5 Trading will benefit investors 
and the national market system by increasing market accessibility, 
promoting capital

[[Page 58191]]

formation, and facilitating portfolio management, including for the 
growing number of retail investors outside of the United States whose 
local business hours do not coincide with U.S. Regular Trading Hours.
    The Exchange further believes the proposal is consistent with the 
Act because the proposed Overnight Trading Session will operate in 
substantially the same manner as the Exchange's existing extended hours 
sessions. All order types, execution processes, membership rules, 
market maker obligations, priority rules, disciplinary rules, clearly 
erroneous execution protections, risk settings, and fat finger 
safeguards applicable to the Exchange's existing sessions will continue 
to apply in full during the Overnight Trading Session. The Exchange 
believes that applying its existing operational and regulatory 
framework to the Overnight Trading Session is consistent with the Act's 
goals of ensuring market integrity, investor protection, and fair and 
orderly trading. The Exchange represents that its systems have the 
capacity to accommodate the proposed 23x5 Trading functionality.
Session Definitions and Order Entry Framework
    The Exchange believes that the proposed new definitions, including 
the Overnight Trading Session and Equity Data Plans, would remove 
impediments to and perfect the mechanism of a free and open market and 
a national market system by adding clarity and transparency to the 
Exchange's rules. The proposed Overnight Trading Session definition, 
anchored to the concept of a ``night preceding a business day'' rather 
than enumerated calendar days, provides a durable and flexible 
framework that accommodates the Exchange's trading calendar without 
requiring recurring conforming amendments. The Exchange believes these 
definitional additions facilitate the understanding of and compliance 
with Exchange rules, thereby removing potential confusion and promoting 
just and equitable principles of trade.
    The Exchange believes the proposed streamlined order entry 
framework under Rule 11.1(a) similarly removes impediments to the 
mechanism of a free and open market by adding the Overnight Trading 
Session to the fulsome list of trading sessions offered by the Exchange 
during which orders may be entered, canceled, modified, executed on or 
routed away from the Exchange, and replacing the Exchange's current 
operating hours with the new operating hours which include the 
Overnight Trading Session. The proposed trading session designation 
requirement under Rule 11.1(a)(1) promotes transparency and investor 
protection by ensuring that each order is clearly designated for the 
session(s) in which it will remain eligible to participate, consistent 
with the approach taken by other national securities exchanges that 
have adopted or sought to adopt extended overnight trading 
frameworks.\29\
---------------------------------------------------------------------------

    \29\ See supra notes 5 and 6.
---------------------------------------------------------------------------

    The Exchange believes that the proposed introduction of a defined 
term ``business day'' in Rule11.1(b), together with the codification of 
the concept of an Early Market Close and the corresponding adjustments 
to the Exchange's trading calendar, is consistent with Section6(b)(5) 
of the Act because these amendments remove impediments to and perfect 
the mechanism of a free and open market and a national market system. 
As proposed, a ``business day'' is any day the Exchange is open for 
trading, each Monday through Friday that is not a holiday, thereby 
providing a clear and predictable foundation for determining when the 
Overnight Trading Session will operate. This definition, which does not 
rely on enumerated calendar days, enhances transparency and flexibility 
by ensuring that the commencement of the Overnight Trading Session is 
tied to whether the following day is a trading day rather than to fixed 
days of the week. The proposed amendment also provides that the 
Exchange will be open for the transaction of business on each business 
day, including the Overnight Trading Session on the preceding calendar 
day, thereby confirming the full scope of Exchange operations under the 
23x5 framework and providing Members with a clear and comprehensive 
statement of when the Exchange is open. This structure accommodates 
holiday closures, holiday-observed weekends, and unforeseen non-
business days without requiring further amendments to the session 
definition. Likewise, the proposal's integration of Early Market Close 
days (under which Regular Trading Hours conclude at 1:00 p.m. and the 
Post-Market Session ends at 5:00 p.m., with the market closure becoming 
effective on the calendar day preceding the closure date) provides that 
the transition into the Overnight Trading Session remains orderly, 
predictable, and aligned with the modified market-wide trading 
schedule. Together, these provisions provide Members with a uniform, 
rules-based mechanism for determining when the Exchange will commence 
and pause trading under the proposed 23x5 framework, promote just and 
equitable principles of trade by reducing uncertainty and the risk of 
misaligned order entry during session transitions, and foster 
cooperation and coordination with other market participants and 
infrastructure providers by grounding the Overnight Trading Session in 
a clear and durable trading-day framework. Accordingly, the Exchange 
believes the proposed amendments are consistent with the protection of 
investors and the public interest because they provide predictable and 
transparent operational parameters for the launch and operation of the 
Overnight Trading Session.
Contingency on Equity Data Plan Readiness
    The Exchange believes that conditioning commencement of the 
Overnight Trading Session on satisfaction of the Equity Data Plan 
readiness requirements set forth in proposed Rule 1.5(i) is consistent 
with the Act and, in particular, with the Act's requirements that 
exchange rules be designed to prevent fraudulent and manipulative acts 
and practices, foster cooperation and coordination with persons engaged 
in regulating, clearing, settling, and processing information with 
respect to securities transactions, and perfect the mechanism of a free 
and open market and a national market system. As the Commission has 
recognized in approving similar conditions for other exchanges seeking 
to operate overnight sessions, this requirement is designed to 
reasonably ensure that consolidated quotation and transaction data are 
provided in a manner consistent with existing extended hours sessions, 
and that trading will not occur until the infrastructure necessary to 
support fair and orderly markets during overnight hours is in 
place.\30\ Prior to commencing operation of the Overnight Trading 
Session, the Exchange will confirm via a subsequent Section 19(b) 
filing that the Equity Data Plans are prepared to collect, consolidate, 
process, and disseminate quotation and transaction information at all 
times during the Overnight Trading Session and that the Exchange is 
able to comply with its obligations under the Act during those hours. 
The Exchange believes this approach promotes transparency because 
trading will not commence until these conditions are verified and 
publicly filed.
---------------------------------------------------------------------------

    \30\ Id.

---------------------------------------------------------------------------

[[Page 58192]]

Order Type Eligibility
    The Exchange believes the proposed conforming amendments to its 
Limit Order and Pegged Order order type rules are consistent with the 
Act because they include the Overnight Trading Session in addition to 
the Pre-Market, Market, and Post-Market Sessions, thereby ensuring a 
consistent and investor-protective trading environment across all 
extended hours sessions.
Weekday Trading Pause
    The Exchange believes the proposed Weekday Trading Pause under new 
Rule 11.24 is consistent with the Act because it promotes the 
protection of investors and the public interest by providing the 
Exchange and market participants with a defined period each weekday to 
conduct maintenance and testing, process pending corporate actions, and 
clear end-of-day positions before a new trading day commences. The 
cancellation of all resting orders at the end of the Post-Market 
Session at 8:00 p.m. each weekday promotes investor protection by 
ensuring that Members must affirmatively re-enter orders for the 
following trading day, reducing the risk of unintended executions based 
on stale order instructions.
Customer Disclosures
    The Exchange believes proposed Rule 3.21(h) is consistent with the 
Act and, in particular, with the Section 6(b)(5) requirement that 
exchange rules be designed to promote just and equitable principles of 
trade, remove impediments to and perfect the mechanism of a free and 
open market and a national market system, and protect investors and the 
public interest. The seven categories of risk disclosure required by 
proposed Rule 3.21(h) (addressing the absence of primary listing market 
oversight during overnight hours, the potential for more limited 
regulatory protections, limited trading alternatives, risks associated 
with near-continuous trading, the closure of financial market 
infrastructure companies during overnight hours, the novel nature of 
overnight exchange trading, and potential unforeseen risks) are 
tailored to the specific characteristics of the Overnight Trading 
Session and the Pre-Market Session, and are substantially similar to 
the disclosures required by the Commission in approving the rules of 
other national securities exchanges operating on an extended overnight 
basis.\31\ The Exchange believes that requiring these disclosures will 
enhance transparency and enable investors to make informed decisions 
about whether participating in the Overnight Trading Session or the 
Pre-Market Session is appropriate for them, consistent with the 
investor protection objectives of the Act. These proposed disclosures 
are also consistent with FINRA Rule 2265, which separately requires 
brokers to affirmatively disclose to investors that extended hours 
trading carries greater risks than trading during Regular Trading 
Hours.
---------------------------------------------------------------------------

    \31\ See supra notes 5 and 6.
---------------------------------------------------------------------------

Market Surveillance
    The Exchange believes that extending its existing surveillance 
programs and compliance infrastructure to the Overnight Trading Session 
is consistent with the Act because it provides that trading during 
overnight hours is subject to the same comprehensive regulatory 
oversight applicable to trading during other sessions, including 
automated trade surveillance, routine Member examinations, and an exam-
based regulatory program. Exchange staff will be available during the 
Overnight Trading Session to maintain a fair and orderly market, issue 
necessary rulings, implement trading halts, and take any other action 
that may be necessary, consistent with the Exchange's obligations under 
the Act and its rules.
Competitive Considerations
    The Exchange also believes the proposal is consistent with the Act 
because it will foster competition by providing investors with access 
to another regulated national securities exchange that offers trading 
during overnight hours, consistent with similar proposals approved by 
the Commission for other national securities exchanges. The Exchange 
operates in a highly competitive market in which investors seeking 
overnight access to U.S. equities currently resort to alternative 
trading systems, foreign securities markets, and other venues. Enabling 
23x5 Trading on the Exchange will allow it to compete for order flow 
from these investors, which the Exchange believes will increase market 
accessibility, promote capital formation, and facilitate portfolio 
management.

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 Exchange believes the 
proposed rule change will, in fact, enhance competition by providing 
investors with access to an additional regulated national securities 
exchange offering trading during overnight hours.
    The Exchange does not believe the proposed rule change will impose 
any burden on intramarket competition that is not necessary or 
appropriate in furtherance of the purposes of the Act. The Overnight 
Trading Session will be available to all Members on an equal and non-
discriminatory basis. All Members will have the same opportunity to 
enter orders, access liquidity, and participate in trading during the 
Overnight Trading Session under the same rules, order type eligibility 
requirements, and session designation framework applicable to all other 
Exchange trading sessions. The proposed customer disclosure 
requirements under Rule 3.21(h) will similarly apply uniformly to all 
Members that accept orders for execution during the Overnight Trading 
Session and Pre-Market Session, ensuring that all customers receive 
consistent information about the risks associated with trading during 
those hours regardless of which Member they use. The proposed rule 
change does not create any special rights, preferences, or advantages 
for any particular class of Member or market participant.
    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. To the contrary, 
the Exchange believes the proposed rule change will promote intermarket 
competition by enabling the Exchange to compete with other national 
securities exchanges and trading venues that currently offer, or are in 
the process of offering, extended overnight trading in U.S. equity 
securities. Investors currently seeking overnight access to U.S. 
equities may resort to alternative trading systems, foreign securities 
markets, or other off-exchange venues. By enabling 23x5 Trading on a 
regulated national securities exchange, the Exchange's proposal 
provides investors with a regulated, transparent, and competitive 
alternative to these venues, which the Exchange believes will benefit 
the national market system.
    As noted above, the Exchange's proposal is substantively consistent 
with similar overnight trading proposals that the Commission has 
previously approved for other national securities exchanges, including 
EDGX, 24X, NYSE Arca, and Nasdaq. The Exchange does not believe that 
its proposal confers any competitive advantage on MEMX relative to 
other exchanges that have received approval for similar frameworks. 
Rather, the Exchange's

[[Page 58193]]

proposal places it on equal competitive footing with those venues, 
which the Exchange believes is necessary and appropriate in furtherance 
of the purposes of the Act.
    Furthermore, the Exchange's proposal to condition commencement of 
the Overnight Trading Session on satisfaction of the Equity Data Plan 
readiness requirements provides that 23x5 Trading will not commence 
until the consolidated data infrastructure necessary to support a fair, 
transparent, and competitive overnight trading market is in place. The 
Exchange believes this condition serves the interests of the national 
market system as a whole and does not impose any burden on competition 
that is not necessary or appropriate in furtherance of the purposes of 
the Act.

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

    The Exchange neither solicited nor received comments on the 
proposed rule change.

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

    The proposed rule change is filed for immediate effectiveness 
pursuant to Section 19(b)(3)(A) of Act \32\ and Rule 19b-4(f)(6) \33\ 
thereunder. The Exchange designates that the proposed rule change 
effects a change that (i) does not significantly affect the protection 
of investors or the public interest; (ii) does not impose any 
significant burden on competition; and (iii) by its terms, does not 
become operative for 30 days after the date of the filing, or such 
shorter time as the Commission may designate if consistent with the 
protection of investors and the public interest. In addition, the 
Exchange provided the Commission with written notice of its intent to 
file the proposed rule change, along with a brief description and text 
of the proposed rule change, at least five business days prior to the 
date of filing, or such shorter time as the Commission may designate.
---------------------------------------------------------------------------

    \32\ 15 U.S.C. 78s(b)(3)(A).
    \33\ 17 CFR 240.19b-4(f)(6).
---------------------------------------------------------------------------

    As discussed above, the proposal is based on EDGX's filing, and 
other exchanges have similarly received approval to offer 23x5 
trading.\34\ Accordingly, the Exchange believes that the proposed rule 
change is non-controversial and eligible to become effective 
immediately because it would enable the Exchange to adopt a similar 
framework for 23x5 trading as the previously aforementioned exchanges. 
Moreover, the proposed change would promote the maintenance of a fair 
and orderly market and the protection of investors and the public 
interest. The proposed amendments are narrowly tailored to accommodate 
the framework of 23x5 trading that has been approved by the Commission 
while preserving the integrity, efficiency, and investor protections of 
the Exchange's existing trading rules. The Exchange also believes that 
the proposed rule change would not significantly affect the protection 
of investors or the public interest or impose any significant burden on 
competition because the changes are based on the approved rules of 
another national securities exchange that the Exchange proposes to 
adopt in substantially similar form. The differences between the 
proposed rules and EDGX's rules described above are based on different 
functionality offerings but ultimately are not inconsistent with the 
shared purpose of enabling 23x5 trading, which promotes competition and 
is in the interest of investors and the investing public.\35\
---------------------------------------------------------------------------

    \34\ See supra notes 5 and 6.
    \35\ As noted, these differences include order queuing 
functionality which the Exchange does not provide, as well as 
differences in order types and modifiers as well as certain session 
restrictions related thereto.
---------------------------------------------------------------------------

    For all the foregoing reasons, this rule filing qualifies for 
immediate effectiveness as a ``non-controversial'' rule change under 
paragraph (f)(6) of Rule 19b-4.\36\ 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: (i) necessary or appropriate in the public 
interest; (ii) for the protection of investors; or (iii) 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) \37\ of the Act to determine whether the proposed rule 
should be approved or disapproved.
---------------------------------------------------------------------------

    \36\ 17 CFR 240.19b-4(f)(6).
    \37\ 15 U.S.C. 78s(b)(2)(B).
---------------------------------------------------------------------------

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

    <bullet> Use the Commission's internet comment form (<a href="https://www.sec.gov/rules/sro.shtml">https://www.sec.gov/rules/sro.shtml</a>); or
    <bullet> Send an email to <a href="/cdn-cgi/l/email-protection#196b6c757c347a7674747c776d6a596a7c7a377e766f"><span class="__cf_email__" data-cfemail="ee9c9b828bc38d8183838b809a9dae9d8b8dc0898198">[email&#160;protected]</span></a>. Please include 
file number SR-MEMX-2026-28 on the subject line.

Paper Comments

    <bullet> 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-MEMX-2026-28. 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 (<a href="https://www.sec.gov/rules/sro.shtml">https://www.sec.gov/rules/sro.shtml</a>). 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-MEMX-2026-28 and should be submitted on 
or before October 5, 2026.

    For the Commission, by the Division of Trading and Markets, 
pursuant to delegated authority.\38\
---------------------------------------------------------------------------

    \38\ 17 CFR 200.30-3(a)(12).
---------------------------------------------------------------------------

Sherry R. Haywood,
Assistant Secretary.
[FR Doc. 2026-18662 Filed 9-11-26; 8:45 am]
BILLING CODE 8011-01-P


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Indexed from Federal Register on September 14, 2026.

This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.