Why Shifting to Continuous Trading Hours Isn’t a Switch: The ATS Operator’s Path to 23x5 and Beyond

By Nicole Collins, AVP – Product Strategy

The conversation around expanded trading hours is getting louder — and more practical. In my peer discussions with senior leaders who build and operate U.S. equities trading platforms (ATSs, SDPs and exchanges), the most consistent takeaway is that 23x5 is not a single event. 

It’s an operating model shift that touches everything: technology, compliance coverage, incident response and the assumptions we’ve traditionally relied on regarding maintenance windows and downtime. As always-on markets evolve, operators are increasingly focused on the operational journey:

• How will global trading hours interact with liquidity formation and market quality?
• How will a longer trading day raise the bar for resiliency and regulatory readiness?
• How will change force hard decisions about infrastructure strategy and AI governance?

These topics are deeply interconnected; treating them as separate workstreams is becoming less feasible and harder to justify. As 23x5 implementation nears, leading institutions are assessing their planning and modernization strategies.
 

Near-continuous trading is often discussed as a binary: either markets move to 23x5 or they don’t. In practice, readiness is much more uneven. Operators are weighing the potential upside — new liquidity windows, improved global investor risk management, and broader competitiveness — against the associated risks: liquidity fragmentation, volatility during off-peak periods, wider spreads and increased execution risk for institutions.

This trade-off is shaping how different firms plan timelines, address participant adoption and evaluate whether continuous hours will improve market quality or simply stretch existing liquidity across more hours.

It’s also important to note that regulatory considerations and dependencies are tightly coupled to today’s market hours. Operational readiness, compliance frameworks, market data availability and the surrounding ecosystem all influence what “safe” progress looks like. Regulators must balance innovation and investor protection, and global alignment questions add complexity for firms operating across jurisdictions.
 

One gap I see in a lot of industry commentary is the assumption that ATS operators are a single category. They aren’t.

In peer conversations, a clear segmentation pattern emerged:

• Bank-operated ATSs tend to have more governance layers, more internal stakeholders and often a more conservative posture around operational changes that impact risk controls and compliance oversight.
• Non-bank / boutique operators often feel a different pressure: moving quickly to differentiate, keep pace with more agile competitors and respond to client expectations on timelines that don’t always map neatly to legacy infrastructure constraints.

If you strip away the headlines, the core “23x5” questions operators are wrestling with include:

• What prerequisites are non-negotiable for expanded hours to be viable?
• How do we protect market quality and avoid destabilizing liquidity fragmentation?
• What does operational excellence look like when downtime windows shrink and incidents still happen?
• Where are regulators likely to focus as market structure evolves?

The industry framing is clear. While continuous trading hours could unlock benefits, implementation challenges are real. Technology, staffing, surveillance, compliance and broader dependencies must evolve together to address roadblocks.

A practical approach is to treat readiness as achieving a set of capabilities, rather than reaching a fixed date on a calendar. At a high level, operators consistently come back to three dimensions of readiness:

1. Operational readiness (coverage models, incident response, change control)
2. Technology readiness (resilience, performance under new operating patterns)
3. Compliance readiness (auditability, reporting expectations, regulator engagement) 

Those are not new ideas — but global trading hours compress the margin for error, which makes the gaps more visible.
 

Another theme that’s tied to “always-on” is infrastructure as a strategic driver. The debate operators face is larger than “What’s our tech stack?” It’s “What constraints does our infrastructure impose on our roadmap — and how quickly can we change that?”

Operators are increasingly scrutinizing the return on infrastructure spend through the lenses of latency, resiliency, scalability and speed to market. In many organizations, infrastructure is becoming a board-level topic rather than a purely technical one.

The architectural implications are also becoming more explicit:

• On-prem continues to offer deterministic performance and fine-grained control — especially important for latency-sensitive workloads.
• Cloud-enabled approaches promise flexibility and cost alignment, but introduce questions around predictability, data gravity, regulatory acceptance and integration with existing market infrastructure.
• Hybrid models are increasingly seen as pragmatic: keep the most latency-critical components on-prem while using cloud services for analytics, testing, surveillance and disaster recovery, acknowledging that hybrid architectures introduce their own operational overhead and skills requirements.

This is where an emerging tension breaks through: differentiation vs. standardization. Firms want proprietary innovation where it matters (liquidity strategy, client experience, unique order logic) but many of the underlying challenges — resiliency, regulatory readiness, data governance — are shared. That raises a strategic question: Where should operators collaborate on common frameworks, and where should they compete?
 

The most important takeaway from our recent peer dialogue is that market structure evolution and infrastructure strategy are inextricably intertwined.

Decisions made in one area increasingly impact, constrain or enable the others. That is why the most credible operator strategies are moving toward integrated planning.

If you operate an ATS (or a trading platform adjacent to ATS workflows) and you’re building a roadmap for the next 12–24 months, I would recommend three areas of focus when pressure-testing three assumptions:

1. Readiness assumptions: Are you planning to a date, or building the operational and compliance capabilities that make progress safe?
2. Infrastructure constraints: Are provisioning timelines, architectural choices and skills availability aligned with the market timeline you believe is coming?
3. Blockchain/digital asset consideration: Are systems designed with cross-rail connectivity and integration in mind to avoid the gaps in parallel models?

Continuous trading hours is not just a market structure conversation anymore. It’s a test of operating models. The operators who plan for that reality will be best positioned for what comes next.
 

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