Sep. 18, 2026
Vanessa Countryman, Secretary U.S. Securities and Exchange Commission 100 F Street, NE Washington, DC 20549-1090 Submitted via rule-comments@sec.gov Re: File Number 4-913 — Roundtable on Preparations for 24-Hour Trading Dear Secretary Countryman and Commissioners, I am writing as an individual European investor who participates exclusively in U.S. capital markets, to formally comment in opposition to the Commission's move toward 23- and, ultimately, 24-hour equity trading, in connection with the September 17, 2026 roundtable on preparations for 24-hour trading (File No. 4-913), and in relation to the related approvals already granted to Nasdaq (File No. SR-Nasdaq-2025-109, Release No. 34-105199, approved April 10, 2026) and NYSE Arca (File No. SR-NYSEARCA-2024-89, Release No. 34-102400). I recognize that some of these rules have already been approved. I am submitting this letter for the public record because I believe the concerns below warrant continued Commission scrutiny, published monitoring metrics, and a genuine willingness to revisit these approvals if the risks I describe materialize during rollout. Before turning to specifics, I would pose a simple question the Commission should be able to answer clearly: if it ain't broke, why fix it? The traditional trading day has functioned well for decades, with deep, well-understood liquidity, orderly price discovery, and a regulatory and surveillance framework built around it. The case for dismantling that structure should meet a correspondingly high bar — and I do not believe it has. 1. Market Quality and the Value of a Concentrated Opening The traditional market structure — hours before the open for research, news review, and chart analysis, followed by a single opening bell — is not an accident of history but a mechanism that concentrates liquidity and information into one moment. The opening print represents the aggregated judgment of a very large number of participants acting on the same overnight information set at the same time. Fragmenting that process across a 23- or 24-hour session disperses this concentrated price discovery into a thin, continuous trickle. The result is not more information being priced in faster; it is the same information being priced in less efficiently, by fewer participants, against wider spreads. 2. Volatility and Liquidity Risk During Overnight Sessions Overnight and low-volume sessions are already documented to carry materially wider bid-ask spreads and thinner order books than the regular session. Extending this thin-liquidity environment to a full overnight session, five nights a week, structurally increases the risk of exaggerated price moves on modest order flow — precisely the kind of fragility that harms retail investors who are least equipped to navigate it. I do not believe the data feed, SIP, and market-maker infrastructure changes discussed to date are sufficient to offset this risk at full scale. 3. Loss of a Natural Deliberation Window Under the existing structure, when material news breaks after the close, investors have a period of hours to read, discuss, and think before having to act. That deliberation window is a feature, not a flaw — it produces calmer, more considered order flow at the next open rather than reflexive, emotionally driven trades. Continuous trading removes this buffer entirely and pressures investors to react in real time, at all hours, rather than deliberately. 4. Investor and Market Participant Health A defined trading day allows market professionals and engaged retail investors to plan research, risk management, and rest around a known schedule. Round-the-clock trading removes that boundary. A regulator overseeing the national market system has a legitimate interest in market structures that do not implicitly pressure continuous participant availability, given the direct link between sleep, rest, and sound financial decision-making. 5. Regulatory Sequencing Concerns I am concerned that the Commission's general approach — approve first, observe consequences after — inverts the precautionary posture that should apply to a structural change of this magnitude to the National Market System. If overnight liquidity and volatility problems emerge only after retail capital is already exposed to them, any subsequent corrective rulemaking will arrive too late to prevent investor harm. I would ask the Commission to publish, ahead of further expansion, specific pre-committed thresholds (e.g., spread widening, execution quality metrics, retail order fill rates during overnight sessions) that would trigger a formal reassessment or rollback. 6. This Is Not the Same Case as Crypto Markets Proponents of extended hours frequently point to the 24/7 nature of crypto trading as precedent. I would respectfully note the two are not comparable: crypto is a decentralized, speculative asset class without corporate earnings cycles, board governance, or the disclosure regime that underlies equity valuation. Equities are priced against fundamentals that are reported, discussed, and digested on a cadence tied to a defined trading calendar. Applying a 23- or 24-hour trading cadence to an asset class governed by a 9-to-5 disclosure and governance cadence creates a structural mismatch that a purely speculative asset class does not have. I respectfully request that the Commission: (a) enter this letter into the public record for File No. 4-913; (b) commit to specific, published metrics for monitoring overnight liquidity, spread, and volatility as 23- and 24-hour sessions come online; (c) commit to a formal review point within the first 6–12 months of full implementation, with a genuine willingness to modify or reverse these rules if investor harm is demonstrated; (d) weigh, in any further move toward full 23- or 24-hour trading, the cumulative effect on investor decision-making quality and wellbeing, not only on market competitiveness and technical readiness. As a foreign investor whose only access to U.S. equities is through these markets, I have a direct and material interest in the integrity, fairness, and orderliness of the market structure the Commission oversees. Thank you for considering these concerns. Respectfully submitted, Elliot von Börtzell-Szuch Stockholm, Sweden elliot05vbs@gmail.com 09-18-2026