2026-18662NoticeWallet

MEMX Opens Stocks 23/5: Say Goodbye to Market Bedtime

Published Date: 9/14/2026

Notice

Summary

MEMX is shaking up the stock market by letting people trade stocks and ETFs almost all day—23 hours a day, five days a week! This means traders get way more time to buy and sell, making the market more flexible and exciting. The change kicks in right away, so get ready for nearly nonstop action during the workweek!

Analyzed Economic Effects

7 provisions identified: 5 benefits, 2 costs, 0 mixed.

Trading 23 Hours, Five Days a Week

MEMX proposes to permit trading of equity securities and UTP exchange-traded products 23 hours per day, five days per week (23x5 Trading). Under the proposal the Exchange's trading day would run from 9:00 p.m. ET through 8:00 p.m. ET the next calendar day for Sunday 9:00 p.m. ET through Friday 8:00 p.m. ET.

New Overnight Session Hours and Trade Date

The Exchange would add an Overnight Trading Session running from 9:00 p.m. ET on any night preceding a business day to 4:00 a.m. ET on the following calendar day. Trades occurring at or after the 9:00 p.m. start of the Overnight Trading Session will be assigned the trade date of the following calendar day.

Day and GTT Orders Eligible Overnight

The Exchange would accept Day orders entered during the Overnight Trading Session (beginning at 9:00 p.m. ET) and those Day orders would remain eligible for execution through the Overnight Trading Session, Pre-Market Session, and Regular Trading Hours, expiring at the end of Regular Trading Hours (4:00 p.m. ET). The Good-'til Time (GTT) instruction would also be permitted for orders entering beginning with the Overnight Trading Session.

Pegged Orders Must Have Limit Outside RTH

The Exchange would require that any Pegged Orders entered outside of Regular Trading Hours (i.e., during the Overnight Trading Session, Pre-Market Session, or Post-Market Session) include a limit price; Pegged Orders without a limit price will be rejected during those sessions.

Mandatory Overnight Trading Risk Disclosures

The Exchange would add Rule 3.21(h) requiring Members to disclose seven specific categories of risks to customers before accepting orders for the Overnight Trading Session and Pre-Market Session, including risks from limited regulatory surveillance, closed market infrastructure, limited trading alternatives, and the novel nature of overnight exchange trading.

Daily 8:00–9:00 p.m. Pause Cancels Orders

Under the proposal the Exchange will pause trading each weekday between 8:00 p.m. ET and 9:00 p.m. ET; all orders outstanding on the MEMX Book at 8:00 p.m. will be cancelled and the Exchange will resume accepting orders at 9:00 p.m. ET.

Existing Safeguards Apply Overnight

The Exchange states that its existing protections — including surveillance programs, risk settings, single-order price/size protections, clearly erroneous execution rules, trading halt procedures, and other safeguards — will apply in full during the Overnight Trading Session.

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Key Dates

Published Date
9/14/2026

Department and Agencies

Department
Independent Agency
Agency
Securities and Exchange Commission
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