Jul. 23, 2026
July 23, 2026 Vanessa A. Countryman Secretary U.S. Securities and Exchange Commission 100 F Street, N.E. Washington, D.C. 20549-1090 Re: File No. 4-913 - Roundtable on Preparations for 24-Hour Trading Dear Ms. Countryman: I appreciate the opportunity to comment on the Commission's September 17, 2026 Roundtable on Preparations for 24-Hour Trading. I support broader, globally accessible trading hours, provided that the transition is designed as a market-wide change in temporal market structure - not merely as an extension of venue operating hours. I submit this comment as an independent researcher focused on market structure, AI-driven market behavior, and the control and interface layers of financial infrastructure. W-Axis Lab is an independent research initiative, and the views expressed here are my own. I do not represent an exchange, broker-dealer, issuer, or other market intermediary. The central principle is straightforward: clock time should not determine the quality of investor protection. A near-continuous market should provide time-zone-neutral access, but it should also provide time-zone-neutral transparency, surveillance, execution quality, operational resilience, and accountability. 24-HOUR ACCESS WITHOUT A 24-HOUR PROTECTION GAP A near-continuous market is not merely a longer trading day. It is a new temporal market structure in which liquidity, price discovery, supervision, reference data, corporate actions, customer support, and increasingly automated order flow may function differently across the clock. The Commission should therefore treat time as a first-class dimension of market structure. I respectfully recommend that the Commission organize its work around the following eight priorities. 1. Establish a Minimum Viable National Market System for overnight trading. National securities exchanges should not commence broad overnight sessions until the essential national-market-system components can operate on a coordinated basis. The readiness matrix should include the securities information processors, the Consolidated Audit Trail, FINRA trade-reporting facilities, NSCC clearing and risk management, limit-up/limit-down protections, clearly erroneous trade rules, trading halts and resumptions, corporate-action and reference-data processes, and market-wide incident communications. A collection of venues can remain technically open while the national market system is only partially present. That distinction is most dangerous when investors assume that the protections and information environment of the regular session continue unchanged overnight. 2. Create a temporal best-execution and market-quality framework. Execution quality should be evaluated separately for overnight, pre-market, regular-hours, and post-market sessions. Blended monthly statistics may conceal material differences in effective spreads, realized spreads, executable depth, price improvement, routing competition, fill and rejection rates, outages, and clearly erroneous trade outcomes. The Commission should consider session-specific Rule 605 and Rule 606 reporting, or parallel disclosures, so that customers and regulators can determine whether the quality of execution materially changes by time of day. 3. Require dynamic, decision-useful retail context. Static extended-hours warnings are not sufficient for a market that may be available nearly continuously. At the point of order entry, retail investors should receive concise information regarding the current spread, visible depth, status of the consolidated reference price, scope of accessible venues, applicable overnight price-band regime, and whether the security's liquidity is materially thinner than during the regular session. The objective is not disclosure volume. It is decision quality. Interface design should not make a materially different market appear identical merely because the same order ticket is used. 4. Build an information-parity and corporate-actions protocol. In a near-continuous market, the phrase "after the close" loses much of its operational meaning. The Commission and the self-regulatory organizations should establish coordinated protocols for material issuer announcements, earnings releases, mergers, bankruptcies, regulatory decisions, cyber incidents, trading halts, resumptions, symbol and reference-data changes, dividends, splits, ETF net asset values and baskets, and index events. The industry also needs a common definition of trade date, business date, and effective time across exchanges, broker-dealers, clearing agencies, transfer agents, issuers, and data vendors. A disciplined daily maintenance and reference-data boundary remains necessary even in a 23x5 market. 5. Stress-test automated and AI-mediated order flow. The thinnest periods of the day may become increasingly dependent on automated market makers, algorithmic routers, portfolio agents, and AI-assisted trading systems. Firms should test scenarios involving common-model reactions, stale or erroneous data, third-party model or cloud outages, vendor concentration, runaway order generation, synchronized liquidity withdrawal, and conflicts or delays in kill-switch authority. The Commission need not require public identification of every automated order. It should, however, ensure that regulated entities retain sufficient non-public information to reconstruct material automated activity and determine whether correlated machine behavior contributed to a disorderly event. Operational resilience should also be evaluated as a follow-the-sun control problem. Responsibility may move among regional teams while the market remains open. The Commission should ask who has immediate authority to intervene, whether the responsible team has access to the full surveillance and risk context, and how accountability is preserved across handoffs. 6. Coordinate cross-asset and funding-market readiness. Continuous equity prices affect options, securities lending, margin, collateral, ETF creation and redemption, structured products, and portfolio-risk systems. The Commission should examine whether options market makers and clearing members can hedge and finance overnight moves reliably; whether securities-borrow and locate processes operate across the same window; how ETF arbitrage functions when underlying or foreign markets are closed; and whether clearly erroneous and bust policies are coordinated across cash and derivative markets. A long equity session should not create risk transfers into markets whose operating hours, liquidity, or error-correction mechanisms remain misaligned. 7. Use phased security eligibility and a reversible pilot. Initial overnight eligibility should favor highly liquid NMS securities and diversified ETFs that meet objective standards for spreads, depth, market-maker participation, consolidated data, price-band operation, operational readiness, and corporate-action simplicity. Expansion should depend on demonstrated market quality rather than commercial demand alone. If spreads, error rates, manipulation alerts, outages, customer-harm indicators, or concentration metrics exceed predetermined thresholds, the Commission and the SROs should be able to narrow eligibility, modify protections, or pause expansion without disrupting the regular session. 8. Publish a recurring temporal market-quality dashboard. A public dashboard should compare sessions using, at minimum: quoted and effective spreads; displayed and executable depth; price impact; price improvement; volume and venue concentration; active liquidity-provider counts; fill, rejection, cancellation, and timeout rates; outages and recovery time; clearly erroneous trades; price-band and halt events; CAT and TRF exceptions; corporate-action and reference-data errors; customer complaints; retail-versus-institutional execution differences where measurable; cross-asset disruptions; and material automated-order interventions available to regulators. The dashboard should be segmented by security type, venue, and time band. The success test should not be whether systems remain open. It should be whether reliable prices, comparable protections, effective surveillance, and accountable operations remain active whenever the market is open. QUESTIONS THE ROUNDTABLE SHOULD PUT ON THE RECORD 1. What minimum set of SIP, CAT, TRF, clearing, LULD, corporate-action, and reference-data capabilities must be simultaneously operational before an exchange opens overnight? 2. What is the authoritative definition of trade date, business date, and effective time across exchanges, brokers, clearing agencies, transfer agents, and issuers? 3. Should Rule 605 and Rule 606 reporting, or parallel disclosures, be segmented by overnight and other extended-hours sessions? 4. What point-of-trade information would materially improve retail decisions without creating disclosure overload? 5. How should material issuer announcements, halts, and resumptions operate when there is no meaningful after-hours period? 6. What common maintenance window and reference-data process is required to prevent symbol, corporate-action, and pricing errors? 7. How should the Commission test correlated automated or AI-mediated behavior, third-party concentration, and autonomous order generation? 8. How should equity overnight trading interact with options, securities lending, margin, collateral, ETF arbitrage, and foreign-market hours? 9. Which objective eligibility and exit criteria should govern a phased pilot? 10. What public dashboard will allow investors and the Commission to determine whether overnight access is improving market quality or merely redistributing liquidity and risk? CONCLUSION The United States has an opportunity to make its equity markets more globally accessible while extending the institutional strengths that make those markets trusted. The transition should not be judged solely by whether trading systems remain available. It should be judged by whether investors retain reliable prices, comparable execution protections, effective surveillance, accountable operations, and a coherent national market system at every hour the market is open. Twenty-four-hour access should not produce a twenty-four-hour protection gap. The Commission can avoid that outcome by treating time as a first-class dimension of market structure and by requiring a coordinated, measurable, and reversible transition. Respectfully submitted, Amy Li Independent Researcher, W-Axis Lab New York, New York control-layers.pages.dev Selected primary materials considered include the Commission's July 23, 2026 announcement for File No. 4-913; speeches by Division of Trading and Markets Director Jamie Selway concerning shared infrastructure and 23x5 readiness; DTCC's June 29, 2026 implementation of extended NSCC clearing hours; FINRA's 2026 Annual Regulatory Oversight Report and Regulatory Notices 25-15 and 26-07; the Commission's approvals and NMS actions concerning Nasdaq extended trading and overnight price-band protections; and public comment letters submitted by IEX, SIFMA, Better Markets, and Professor Haoxiang Zhu in the related extended-hours market-structure record.