Nasdaq is continuing to build the infrastructure for a market that trades nearly around the clock.

On August 20, 2026, the Securities and Exchange Commission published a Nasdaq rule filing that addresses an important piece of the exchange’s planned 23/5 trading model: the market data Nasdaq will use to handle, route, and execute orders during its new overnight trading session.

The change may appear technical, but it is another indication of how U.S. securities markets are adapting to investor demand for trading outside traditional market hours.

Nasdaq’s Move Toward 23/5 Trading

Earlier this year, the SEC approved Nasdaq’s proposal to expand trading in NMS stocks and exchange-traded products to 23 hours per day, five days per week.

Under the approved framework, Nasdaq’s trading day will generally be divided into:

• Day Session: 4:00 a.m. to 8:00 p.m. ET

• Day-to-Night Pause: 8:00 p.m. to 9:00 p.m. ET

• Night Session: 9:00 p.m. to 4:00 a.m. ET

The one-hour pause gives Nasdaq and market participants time for maintenance, testing, clearing, corporate actions, and the transition to the next trading day.

The Night Session is expected to begin on Sunday evenings at 9:00 p.m. ET and continue through the weekday trading cycle.

Importantly, Nasdaq cannot simply switch on overnight trading immediately. Its rules condition the launch on, among other things, the availability of the Securities Information Processor infrastructure necessary to collect, consolidate, process, and disseminate quotation and transaction information during the Night Session.

What Is Nasdaq Changing?

The latest filing focuses on Nasdaq Equity Rule 4759(a).

That rule identifies the quotation data Nasdaq uses for functions including:

• order handling;

• order routing;

• execution; and

• regulatory compliance processes associated with those activities.

Under Nasdaq’s existing framework, its system uses designated proprietary and network processor feeds, with primary and secondary data sources established for different market centers.

For the new Night Session, Nasdaq proposes something different.

Nasdaq will use CQS/UQDF as the sole source of quotation data for purposes of Rule 4759(a) during the Night Session, subject to the conditions governing the launch of overnight trading.

CQS refers to the Consolidated Quotation System, while UQDF refers to the UTP Quotation Data Feed. Together, these feeds provide consolidated quotation information that Nasdaq can use to support overnight order handling and execution.

Why Use a Different Data Framework Overnight?

Nasdaq's reasoning is primarily operational.

Extending trading into the overnight period requires changes to timestamps used by the exchange's market-data feed handlers. Rather than make those changes across the proprietary feeds that Nasdaq currently relies on during its existing trading hours—and potentially introduce additional operational risk—Nasdaq proposes limiting the necessary changes to CQS/UQDF.

In Nasdaq's view, this gives the exchange a reliable consolidated quotation source for overnight trading while minimizing changes to systems supporting its existing Day Session and other Nasdaq-affiliated markets.

The change is narrowly tailored to the Night Session.

During the Day Session, Nasdaq intends to continue using the existing proprietary and network processor feeds and the primary/secondary source framework already established under Rule 4759.

Why This Matters

The significance of this filing goes beyond which market-data feed Nasdaq uses between 9:00 p.m. and 4:00 a.m.

The broader story is the continued evolution of U.S. markets toward near-continuous trading.

Investors increasingly operate in a global, always-on environment. Digital asset markets already trade 24/7, and international events can move markets long before U.S. exchanges traditionally open.

Nasdaq's 23/5 framework moves traditional securities markets closer to that model.

But expanding trading hours also requires exchanges and regulators to address the infrastructure behind the market: consolidated data, order routing, execution, clearing, corporate actions, regulatory surveillance, and investor protection all have to function reliably during hours when U.S. markets historically have been closed.

This filing addresses one relatively small—but necessary—piece of that infrastructure.

What Does This Mean for Market Participants?

For Nasdaq members, the immediate operational impact of this particular proposal is limited. Nasdaq expressly states that the change does not impose new obligations on members and would apply uniformly to members participating in the Night Session.

The longer-term implications of 23/5 trading, however, are much broader.

Broker-dealers, trading platforms, fintech companies, investment advisers, and other market participants may need to consider how expanded trading hours affect their own systems and policies, including:

• execution and routing procedures;

• market-data infrastructure;

• supervisory and compliance systems;

• staffing and operational coverage;

• risk management;

• disclosures regarding extended-hours trading; and

• best-execution considerations.

Extended-hours markets can also present different liquidity, volatility, and pricing dynamics than traditional market hours. As 23/5 trading develops, firms offering customers access to these sessions will need to consider how their regulatory obligations operate in an increasingly continuous market environment.

The Bigger Picture: Traditional Markets Are Becoming More “Always On”

For fintech and digital asset companies, Nasdaq's move is particularly noteworthy.

Crypto markets normalized the concept that an asset can trade continuously across jurisdictions and time zones. Traditional securities markets, by contrast, have historically operated around a defined U.S. trading day.

That distinction is gradually narrowing.

Nasdaq's planned 23/5 model does not create a fully 24/7 securities market, and significant differences remain between traditional securities infrastructure and digital asset markets. But the direction of travel is increasingly clear: market infrastructure is being redesigned for investors who expect access beyond the traditional 9:30-to-4 trading window.

For founders building trading, brokerage, tokenization, market-data, and financial infrastructure products, that evolution creates both opportunities and new compliance questions.

What Happens Next?

Nasdaq filed the proposed rule change with the SEC on August 17, 2026, and the Commission published notice on August 20.

The rule change was filed for immediate effectiveness, although the broader launch of Nasdaq's Night Session remains subject to the conditions contained in Nasdaq's previously approved 23/5 trading framework.

The SEC is also soliciting public comments on the proposal.

For market participants, the filing is another development worth watching as exchanges, regulators, and financial infrastructure providers work through what an increasingly around-the-clock U.S. securities market will look like.

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This blog post is for informational purposes only and is not legal advice. Please consult with a Launch Legal attorney regarding your specific situation.