The planned launch of 23×5 exchange trading on December 6, 2026, marks the most significant extension of operating hours for US national securities exchanges in decades. The SEC and the broader industry have been collaborating to manage the various regulatory and operational requirements necessary to reach this milestone. To address the complexities of this market evolution, the SEC held a roundtable on interest in overnight trading from both retail and international investors, trading venues are working to provide around-the-clock access. Currently, four alternative trading systems—Blue Ocean ATS, Bruce ATS, IBKR Eos ATS, and MOON ATS—already facilitate overnight transactions. SEC staff analysis indicates that while current overnight volume remains modest (roughly 0.9% of total NMS share volume on an average day), it is expanding rapidly, with a 359% year-over-year increase. Consequently, US national securities exchanges are now preparing to enter the overnight equities market.
Exchanges currently operate across three sessions from Monday to Friday: 4:00 am to 9:30 am ET, 9:30 am to 4:00 pm ET, and 4:00 pm to 8:00 pm ET. With the 23×5 expansion, certain exchanges will introduce an overnight session running Sunday through Thursday from 8:00 pm to 4:00 am ET, incorporating a mandatory one-hour pause each evening between 8:00 pm and 9:00 pm ET.
During the roundtable, the Commissioners and the Director of Trading and Markets expressed support for these increased trading opportunities. Chairman Atkins noted that, beyond meeting investor demand, extended hours could offer several benefits, including: (1) aligning US trading hours with international markets; (2) drawing more global capital into the US; (3) allowing investors to respond more quickly to developments, thereby mitigating overnight risk and improving market efficiency; and (4) preventing price discovery distortions caused by trading halts. However, Chairman Atkins emphasized that such major shifts must strike a balance between market access and investor protection. The following initiatives by market participants are designed to maintain that equilibrium.
B. Implementation of 23×5 Exchange Trading
The rollout of 23×5 trading has been a comprehensive, coordinated effort involving both regulators and market participants. The following points outline the key steps taken or currently underway to broaden trading access for investors.
To date, the SEC has granted conditional approval to five national securities exchanges—24X, Cboe EDGX, MEMX, Nasdaq, and NYSE Arca—to offer 23×5 trading, enabling participants to trade equities 23 hours a day, five days a week, by adding an overnight session. Trading has not yet begun, however, as the SEC’s approvals were contingent upon the readiness of the Equity Data Plans for consolidated market data (“SIPs”) to receive and disseminate quotes and trades during overnight hours just as they do during standard sessions. Exchange representatives at the roundtable confirmed that those planning to launch overnight trading remain on schedule for the December 6, 2026, SIP readiness date.
On June 26, 2026, the SEC approved amendments to national market system plans, allowing SIPs to extend their operating hours to 9:00 pm ET Sunday through 8:00 pm ET Friday, excluding holidays, with a one-hour technical refresh pause at 8:00 pm ET Monday through Thursday. The approval orders established December 6, 2026, as the launch date for 23×5 trading. Since that time, the SIPs have reaffirmed this commencement date and provided further implementation guidance. Exchange representatives also confirmed the December 6, 2026, timeline during the roundtable.
Another critical factor for 23×5 trading is the clearance and settlement of overnight transactions. The NSCC, which serves as the central counterparty for US equity securities, sought and received SEC approval to extend its clearing services to a 24×5 schedule, operating from Sunday at 8:00 pm ET to Friday at 8:00 pm ET to support overnight activity. On June 29, 2026, the NSCC announced that it was live for these extended hours.
4. Corporate Action Information
Under the current structure, listing exchanges process corporate action updates during the overnight period when markets are closed. Other participants, such as broker-dealers, also utilize this time to adjust quotes, orders, and internal systems. With the shift to 23×5 trading, the one-hour pause between 8:00 pm and 9:00 pm ET may not provide sufficient time to process complex corporate actions. To mitigate this, primary listing markets have adopted harmonized rules for mandatory regulatory halts for securities undergoing specific corporate actions. These rules are intended to provide enough time for exchanges and participants to update systems and reference data, and they are expected to become operative alongside the launch of 23×5 trading.
Under these new rules, if a security is impacted by one of the nine specified corporate actions, the listing exchange will implement a mandatory halt between 8:00 pm and 9:00 pm ET on the day before the action becomes effective. These halts will be disseminated via the SIPs and will remain in effect throughout the overnight session. The primary listing market will reopen the security at 8:00 am ET. If a primary listing market initiates a corporate action-related regulatory halt, all other national securities exchanges trading that security must also halt trading.
The nine categories subject to a mandatory corporate action halt include: (1) changes in trading symbol; (2) changes in CUSIP number; (3) large dividends; (4) stock splits (forward or reverse); (5) de-SPAC transactions; (6) spin-offs; (7) changes in security type (e.g., preferred to common); (8) mergers and mandatory share exchanges; and (9) any other event where the primary listing market determines a halt is necessary to maintain fair and orderly markets or protect investors.
5. FINRA’s Trade Reporting Facilities
In conjunction with the extended SIP hours, FINRA’s Trade Reporting Facilities (“TRFs”), which allow members to report over-the-counter trades in NMS stocks, will also extend their operating hours. Currently, these facilities operate from 4:00 am to 8:00 pm ET, Monday through Friday. Starting December 6, 2026, they will operate from 9:00 pm ET Sunday through 8:00 pm ET Friday, with the same one-hour technical pause. As noted in the rule filing, these expanded hours will allow for real-time public dissemination of trade reports for OTC transactions executed during overnight sessions.
Efforts are also underway to support CAT reporting for overnight exchange trading. CAT has published an alert detailing the necessary reporting changes for Industry Members. While existing deadlines for submissions and corrections remain unchanged, the definition of “Trade Date” has been updated to accommodate 23×5 trading. Effective December 6, 2026, the Trade Date for Industry Members will be defined as “the period beginning at 8:00 p.m. Eastern Time on the calendar day immediately preceding Regular Trading Hours and ending at 8:00 p.m. Eastern Time on the same calendar day as Regular Trading Hours.” The alert clarifies that while some exchanges will begin trading on Sunday evening, weekends and holidays will not count as a Trade Date, and events occurring then will be assigned to the next business day. CAT has also updated its technical specifications to reflect these changes.
C. Investor Protection Related to 23×5 Trading
Regulators and market participants have been evaluating investor protection measures for 23×5 trading. These approaches aim to balance expanded access with the need to address periods historically marked by lower liquidity, wider spreads, and potential price volatility.
1. Limit Up Limit Down Plan – Overnight Price Bands
On August 5, 2026, the Commission approved an amendment to the Plan to Address Extraordinary Market Volatility (“LULD Plan”) to account for extended hours. This amendment introduces static “Overnight Price Bands” that will be active from 9:00 pm ET Sunday through Thursday until 4:00 am ET the following day, effective December 6, 2026.
The primary listing exchange for each NMS stock will calculate and disseminate these bands to the SIPs. The bands will be based on two reference prices: the official closing price reported by the listing market and the consolidated last round lot sale as of 7:45 pm ET. The lower band will be set 20% below the lower reference price, and the upper band will be 20% above the higher reference price, subject to minimum size requirements. Unlike the dynamic bands used during regular hours, these overnight bands will remain constant throughout the session. The 20% parameter aligns with the standard currently used by ATSs for overnight trading.
The amendment requires all trading centers operating overnight to maintain policies and procedures designed to prevent trades or price displays outside these bands. While the plan does not mandate automatic trading pauses if a band is hit, primary listing exchanges may declare a regulatory halt if necessary to maintain a fair and orderly market. Any stock halted during the overnight session will not reopen until the following day.
The LULD Plan participants have stated that these Overnight Price Bands are an initial step and that they intend to gather data to develop final recommendations for the overnight session.
2. Extended Hours Trading Risk Disclosures
Exchanges and FINRA require members to provide customers with enhanced disclosures regarding the risks of overnight trading. Exchange rules mandate disclosure of risks such as lower liquidity, higher volatility, price fluctuations, unlinked markets, the exaggerated impact of news, and wider spreads. These disclosures also cover risks associated with trading when primary markets are closed, limited regulatory protections, and the novel nature of overnight exchange trading.
Similarly, FINRA requires firms to provide a risk disclosure statement to customers engaging in extended hours trading. If a firm allows online extended hours trading or account opening, this disclosure must be clearly posted on the firm’s website. Firms must address the six risks enumerated in FINRA Rule 2265 and consider whether additional product-specific disclosures are necessary.
Exchanges planning to implement 23×5 trading have indicated they will rely on their existing “clearly erroneous” rules during overnight sessions, applying the same standards used outside of the 9:30 am to 4:00 pm ET window.
The five exchanges preparing for overnight trading intend to restrict orders to limit prices only. By requiring participants to specify their price, exchanges aim to mitigate risks such as low liquidity and wide spreads that would be more pronounced with market orders.
5. Market Wide Circuit Breakers
Exchanges and FINRA have also reviewed their market-wide circuit breaker rules. These rules trigger trading halts across all US cash equity and options markets during severe market declines, measured by S&P 500 performance during regular hours. Currently, if a Level 3 Market Decline occurs, trading halts for the remainder of the day, with the earliest resumption at 4:00 am ET the following day. After discussions, it was determined that this resumption time should be maintained for 23×5 trading. Consequently, exchanges and FINRA are filing rule changes to ensure that after a Level 3 halt, trading will not resume until 4:00 am ET the next day.
Commissioner Peirce raised concerns during the roundtable regarding how broker-dealers will satisfy their best execution obligations during overnight hours, particularly for retail investors. Best execution obligations apply to all customer transactions regardless of the time of execution. While FINRA has not proposed revisions to its best execution rule, it has requested comment on whether additional guidance is needed to help firms navigate these obligations in the new environment. FINRA reiterated this request for feedback during the roundtable.
7. Supervisory and Other Staffing Obligations
Roundtable participants emphasized that all market participants must evaluate staffing needs, including licensing requirements, for extended hours. This includes coverage for surveillance, market access controls, compliance, technology, and cybersecurity. Broker-dealers must also ensure they meet their supervisory obligations for overnight activity. FINRA indicated that it continues to analyze these regulatory requirements as part of its rule modernization initiative.
During the roundtable, Commissioners and the Director of Trading and Markets stressed that issuers must also prepare for these market changes. Chairman Atkins encouraged issuers to provide feedback on how extended hours might impact the execution of corporate actions, the dissemination of material information, and SEC filing obligations. Commissioner Peirce questioned whether the transition to 23×5 trading would necessitate changes in how issuers handle filings and public disclosures.
E. Possible Future Expansion to 24×7 Trading on Exchanges
In his remarks, the Director of Trading and Markets noted the potential for a future expansion to 24×7 trading. While the current focus remains on 23×5 and no concrete proposals for 24×7 are on the table, market participants are already considering the infrastructure and regulatory changes that would be required to support such a transition.
