Extended Trading and the COO Challenge of 23x5

Why capital markets leaders must rethink post-trade operations, resiliency, and readiness for a near-continuous market

The move toward 23x5 trading in U.S. equities is no longer just a market structure discussion. For capital markets firms, it is becoming a direct test of operational readiness even as the demand picture continues to develop across client segments.

As exchanges, market utilities, and regulators advance the infrastructure needed to support extended trading hours, the implications are reaching well beyond market access. For COOs and senior operations leaders, the real issue is what happens after the trade: how transactions are processed, how exceptions are managed, how books and records are maintained, and how firms preserve resiliency in a market that is moving closer to near-continuous operation.

In other words, 23x5 is not simply about adding more hours to the trading day. It is about compressing the time firms have to complete critical post-trade activities while raising expectations for real-time visibility, control, and client support.

A market structure shift with operating model consequences

The outline of 23x5 trading is becoming clearer. The industry has largely aligned around a trading week running from 9 p.m. Eastern on Sunday to 8 p.m. Eastern on Friday, with a one- hour technical pause from 8 to 9 p.m. Eastern Monday through Thursday. That pause is expected to be critical for maintenance, testing, and resiliency.

But while the market structure itself is taking shape, the harder challenge lies underneath it.

Capital markets firms have already adapted to compressed settlement cycles, elevated volatility, and growing demand for faster processing. In a 23x5 model, those pressures intensify. Processes that once had the evening or even the next day to catch up may soon have only a narrow operating window before trading resumes.

That is why 23x5 belongs on the COO agenda now. The question is not just whether firms can support overnight access. It is whether their operating models can function effectively when the market is available almost continuously, but the time to identify and resolve issues is not.

The batch window problem

One of the clearest challenges tied to 23x5 is the industry’s continued reliance on end-of-day batch processing.

Many post-trade environments were designed for a market with a defined close, followed by a period in which firms could reconcile trades, update positions, run controls, and prepare for the next session. That model becomes much harder to sustain when transactions continue to flow overnight.

For firms that still depend on a “dark window” to complete overnight processing, even modest overnight volumes can create friction. Trade capture, validation, enrichment, balancing, and reporting all need to happen without being blocked by end-of-day cycles. Position-keeping and balances also need to remain current enough to support decision-making across operations, risk, and servicing teams.

For COOs, this is not just a technology issue. It is a control issue. Real-time or event-driven processing is no longer simply a modernization goal. In a 23x5 market, it is becoming essential to maintaining visibility and operational resilience.

Why post-trade readiness will define adoption

Much of the conversation around 23x5 focuses on market access and liquidity, and the question of where client demand will emerge first. Extended hours could allow investors to respond more quickly to geopolitical developments, earnings announcements, and market-moving events outside the traditional session. It may also increase participation from global investors and from U.S. retail investors who want to engage with the market after working hours, even as institutional adoption develops more gradually.

But for capital markets leaders, the more important issue is whether the post-trade environment can support that access at scale.

There is progress across the market. The SIPs have announced go-live plans to support extended hours. FINRA has indicated that trade reporting will align. DTCC is working toward the ability to clear and settle trades on a 23.5-hour basis. These milestones matter because they support transparency and reduce the risk of fragmented downstream processing.

Still, market-level readiness does not solve firm-level readiness.

Each organization must determine how overnight trades will move through its internal systems, when those trades will be validated and reported, how quickly exceptions can be identified, and how downstream processes such as confirmations, correspondent clearing, and client reporting will be handled.

That makes 23x5 a front-to-back readiness question. Which systems still require downtime? Where do manual controls remain embedded? How quickly can operations teams identify and resolve breaks? Are vendors, counterparties, and internal teams aligned around the same assumptions? These are the kinds of questions COOs should be asking now.

Client demand is still taking shape

One reason 23x5 remains such an important strategic issue is that client demand is still evolving. Some brokers are hearing stronger interest from retail investors and early-stage inquiries from institutional clients, particularly during periods of heightened volatility or when market-moving news breaks outside traditional hours. At the same time, many firms say that institutional demand remains cautious, with asset managers still weighing whether greater access offsets concern around overnight liquidity and execution quality. That mixed picture matters. It suggests firms are unlikely to see a uniform adoption curve across client segments, but it also means readiness decisions may need to be made before demand fully materializes.

For COOs, the implication is clear: waiting for a definitive client signal may leave the operating model behind the market. Regardless of how quickly demand develops, firms will still need to address some of the most time-sensitive operational pressure points in the trade lifecycle

Corporate actions: a likely pressure point

If one area captures the operational challenge of 23x5 particularly well, it is corporate actions.

Corporate actions processing has long been one of the most complex and risk-sensitive parts of the post-trade chain. It depends on timely event data, consistent interpretation, and coordinated action across multiple parties. Even in today’s market structure, it remains an area with meaningful manual effort and operational risk.

In a 23x5 environment, the room for delay shrinks.

Industry groups are already discussing which complex corporate actions may require overnight halts and which simpler events could be processed during the one-hour technical pause. But the broader lesson is clear: manual, fragmented approaches will become harder to sustain as operating windows compress.

For COOs, this matters because the risk is not proportional to volume. Overnight trading may remain a small share of total activity initially, but a single corporate actions error can create outsized exposure across operations, client servicing, and risk management.

Beyond processing: risk, funding, and service expectations

The implications of 23x5 extend beyond transaction processing alone.

Longer trading hours raise questions about margining, capital usage, valuation timing, and balance sheet management. Firms with global follow-the-sun models may already manage elements of this today, but a more developed overnight U.S. market could make these pressures more frequent and more visible.

There is also a service expectation component. If clients can trade over a broader window, they may also expect timelier confirmation, more current positions, and faster issue resolution. That means 23x5 is not only a market access issue it is also a service model issue.

This may create a clearer divide between firms that already operate with global resiliency and those still relying on more localized, manual, or batch-dependent processes.

Treat 23x5 as part of a broader transformation agenda

The most important takeaway for senior leaders may be that 23x5 should not be treated as a standalone initiative.

Capital markets firms are already navigating T+1 optimization, treasury clearing, collateral demands, and broader pressure to modernize legacy infrastructure. The operating model changes required for 23x5 overlap with all of those efforts.

That is why the firms best positioned for this shift will be those that use it as a catalyst. Rather than viewing 23x5 as one more market structure project, they can treat it as an opportunity to accelerate work already underway around event-driven processing, real-time books and records, exception reduction, and front-to-back resiliency.

For COOs, the challenge is clear. The market day may be getting longer, but the margin for operational error is getting smaller. The firms that act now will be better prepared not only for 23x5 trading, but for the next wave of market infrastructure change as well.