Nasdaq's Extended 5x23 Trading Framework: Reshaping Market Hours for Global Investors

Nasdaq is preparing to file a proposal with the U.S. Securities and Exchange Commission to dramatically transform its trading operations. The ambitious initiative would shift the market away from its traditional five-day, 16-hour schedule toward a far more expansive model—one that would keep the exchange operational for 23 hours each day. This transition represents one of the most significant structural changes to equity market operations in recent years, driven by the competitive pressures of global 24-hour trading and investor demand for extended market access.

The 5x23 Framework: From 16-Hour Days to Nearly Round-the-Clock Operations

At its core, the 5x23 model introduces a dual-session architecture designed to accommodate trading activity across both traditional and extended hours. The framework fundamentally reimagines when and how investors can access equities and exchange-traded products (ETPs) on the Nasdaq platform. Rather than confining activity to a single consolidated trading window, the new structure segregates the day into distinct operational periods, each with specific characteristics and trading rules.

The daytime segment preserves the familiar market structure that professionals and institutional investors have relied upon for decades. Opening at 4 a.m. Eastern Time, the session includes the traditional pre-market period, the main regular trading session (which commences at 9:30 a.m. and concludes at 4:00 p.m.), and the after-hours trading window extending to 8 p.m. This preservation of established patterns helps minimize disruption to conventional market participants while still expanding overall access.

Nighttime Operations and Weekly Calendar Adjustments

The complementary nighttime session introduces an entirely new trading window, running from 9 p.m. through 4 a.m. the following morning. Trades executed in the 9 p.m. to midnight window are credited to the subsequent calendar day, creating a seamless bridge between consecutive trading days. This innovation effectively compresses the traditional weekend trading gap that has long characterized equity markets.

Under the 5x23 structure, the trading week undergoes significant recalibration. The market week no longer begins at Sunday’s opening bell but rather at 9 p.m. on Sunday evening. The week concludes following Friday’s daytime close at 8 p.m., rather than at the traditional 4 p.m. Friday finish. This realignment creates a 103-hour trading week—substantially longer than the traditional 80 hours—while still maintaining the conceptual framework of Monday through Friday operations.

Market Implications and Competitive Context

The proposal reflects Nasdaq’s strategic response to evolving market dynamics. As global financial centers operate across multiple time zones and electronic trading eliminates traditional geographic constraints, maintaining a constrained trading window has become increasingly obsolete. The 5x23 model positions Nasdaq to compete more effectively with continuous trading mechanisms gaining traction in international markets and addresses persistent investor demand for access to equities outside conventional hours.

If approved by the SEC, the framework would represent a watershed moment for the U.S. equity market structure, fundamentally altering how millions of investors interact with listed securities and fundamentally reshaping the operational landscape of modern stock trading.