U.S. equity markets are advancing toward near “round-the-clock” trading, aiming to provide global participants with unprecedented extended hours access to U.S. equities markets. This evolution presents a significant shift that will impact trading strategies, infrastructure, risk management and operational models for all market participants operating during extended trading hours.

Market landscape

National securities exchanges including NYSE, Nasdaq and CBOE plan to offer extended trading capabilities and the Securities and Exchange Commission (SEC) granted preliminary approval of 24X Exchange for 23×5 trading — 23 hours a day, five days per week. The Depository Trust and Clearing Corporation’s (DTCC) National Securities Clearing Corporation (NSCC) has announced plans to support extended clearing hours of equities trades by mid-2026, and several alternative trading systems (ATSs) already offer extended trading hours for U.S. equities.

SIP announcement 

On May 6, 2025, the Operating Committees of the Securities Information Processors (SIPs) announced it will submit a plan amendment to the SEC to extend the SIPs’ operating hours to support extended trading activity.

The proposed hours of operation are from 8:00 p.m. ET Sunday to 8:00 p.m. ET Friday, excluding holidays, with the incorporation of a one-hour technical pause Monday through Thursday from 8:00 p.m. ET to 9:00 p.m. ET. This proposal marks a critical infrastructure enhancement that aligns data dissemination with the broader push for nearly continuous trading access across U.S. equity markets.

SIFMA recommendations

The SIP announcement is consistent with the recommendations set forth by SIFMA and its members. Earlier this year SIFMA convened task forces made up of industry subject-matter experts to evaluate the operational and market impacts across the equities industry as markets move toward broader adoption of extended trading hours. Through these task forces, SIFMA members identified the following consensus views:

• SIFMA recommends that the US trade date end each day at 8:00 p.m. ET (e.g., any trade between 8:00 p.m. ET and midnight ET on Monday will have a Tuesday trade date and Wednesday settlement date).

• In this expanded trading environment, U.S. equity exchanges will operate 23 hours a day, five days a week, from Sunday at 9:00 p.m. ET to Friday at 8:00 p.m. ET.

• During the week, following a daily one-hour pause between 8:00 p.m. and 8:59:59 p.m. ET, exchange trading will resume at 9:00 p.m. ET.

• A regularly scheduled one-hour maintenance window will provide market participants with time to complete various critical processes before participating in exchange trading sessions with new trade and settlement dates and will support resilience across the equities markets. ATSs will use the same trade date rollover time as exchanges (8:00 p.m. ET).

Importantly, there is a need to allow market participants to opt in or opt out on offering this extended window to their clients, so that firms can invest in offering extended trading hours in a manner commensurate with their business needs.

Foundationally, the alignment of standard start and end times for the trading day and standard exchange operating hours are critical. Given the SIP announcement and industry agreement on these baselines, the industry can now effectively begin to address the range of implementation considerations and operational complexities necessary to support an expansion of exchange trading hours. These include, but are not limited to, settlement processes, corporate actions, risk management, technology infrastructure and industry coordination.

Industry considerations and open questions

As the industry convenes around the optimal future state, there are several questions that will need to be further discussed and resolved, some of which will require partnership and input from the regulators.

• Market rules and governance: clarity on the explicit requirements to safeguard markets including halts, kill-switches/circuit breakers and volatility controls
• Coordination: Support for harmonizing rules across exchanges, ATSs, and regulatory bodies to ensure consistency and minimize fragmentation.
• SIP Dissemination: Expectations around SIP and proprietary data feed dissemination during the extended hours session, including latency, reliability, and infrastructure needs.
• Participant optionality: Confirmation that participation in the extended trading window remains optional for firms, allowing flexibility based on demand and operational readiness.
• Supervision: guidance on how existing supervisory frameworks should be adapted to support trading during extended hours, including staff coverage, algorithm and volume oversight, and supervisory controls.
• Best execution standards: Clarity on how best execution requirements will be assessed for trades occurring in extended hours, where liquidity and available quotes may differ significantly from core market sessions.
• Trade reporting and trade reporting facility (TRF) availability: Regulatory alignment with respect to real-time trade reporting obligations and what must be available through the extended trading day. If so, firms will need to update their systems and control frameworks to meet this increased requirement. This will also require the TRFs to remain open to support trade reporting during extended trading hours, which may include the introduction of new session identifiers or processing windows to distinguish extended trading hours from core market hour activity. Additional clarity is needed on how overnight trades should be handled in the Consolidated Audit Trail (CAT) reporting, including any required system or time-stamp changes to accommodate an extended trading day.
• Recordkeeping, books and records: Direction on whether extended trading hours require changes in recordkeeping systems or retention policies, especially for time sensitive regulatory obligations.
• Corporate actions: Standardization in the treatment of corporate actions and record dates.
• Resiliency: Regulatory expectations around safeguarding extended trading environments, particularly with respect to resiliency, incident response coverage and cyber threat monitoring during extended hours.

What firms can do now

While implementation is dependent on several factors and is likely to take some time, firms can take steps now to evaluate the implications of the proposed extension of the US trading day on their business models. These include:

• Monitor guidance from regulators and exchanges.
• Assess client demand and business strategies for extended trading hours.
• Actively participate in industry discussions to stay abreast of overall progress toward extended trading.
• Initiate firm-wide readiness assessments, ensuring participation from impacted areas including, but not limited to, Business, Market Conduct, Supervision/Surveillance, Compliance, Risk, Operations, and Technology.
• Review risk management capabilities for managing credit, liquidity and operational risk across the extended hours trading cycle, ensuring that risk management frameworks, limits, thresholds and liquidity management processes can support the activity.
• Review global operating models, operational support functions and critical system infrastructure to support overnight trading.
• Ensure a clear understanding of vendor and third-party service provider preparedness efforts and timelines.
• Establish firm-wide governance to foster transparency and accountability across required change efforts.

What SIFMA is doing now

To address the range of open questions and implementation challenges, SIFMA and the industry, in collaboration with the DTCC and the exchanges, will convene working group sessions in the areas of clearing and settlement, market structure, corporate actions, volatility mechanisms, and margin, among others. The sessions will include broad representation across market participants, including broker-dealers, asset managers, data vendors and service providers.

These sessions will look to address infrastructure changes, trade reporting, settlement timing, supervision, risk management, reporting and corporate action processing.

Conclusion

The transition to extended trading hours on national securities exchanges marks a major evolution in the U.S. equity markets. With opportunity comes complexity, and it is critical for firms and exchanges to work together proactively as trading hours change. SIFMA is committed to facilitating a thoughtful and resilient industry-wide transition to the expansion of trading hours on exchanges.

Editor’s Note: For questions regarding SIFMA’s work on extended trading hours, please contact Stephen Byron ([email protected]), Joseph Corcoran ([email protected]), Gerald O’Hara ([email protected]) and Anthony Macchiarulo ([email protected]).

To learn more about how EY teams are addressing the topic, please reach out to Ryan Gomez ([email protected]) and John Boyle ([email protected]).

The views reflected in this article are the views of the authors and do not necessarily reflect the views of Ernst & Young LLP or other members of the global EY organization.

Authors

Stephen Byron is Managing Director, Head of Technology, Operations and Business Continuity at SIFMA.

John Boyle is Principal, Capital Markets Risk & Business Transformation at Ernst & Young LLP.

Ryan Gomez is Senior Manager, Capital Markets at Ernst & Young LLP.