Nasdaq is brewing an all-weather trading revolution, and the Eastern Time Zone will usher in the "5X23" new era

Major news from the US securities market: Nasdaq has officially announced plans to submit filings to the U.S. Securities and Exchange Commission, aiming to break through existing trading time restrictions and create a new trading system framework.

From 16 hours to 23 hours, significant expansion of trading hours

Currently, Nasdaq’s stock and exchange-traded product (ETP) trading is limited to Monday through Friday, operating 16 hours daily. The new “5X23” plan will fundamentally change this pattern, expanding trading hours to five days a week, 23 hours a day, operating around the clock, with only a 3-hour maintenance window from 1 a.m. to 4 a.m.

For trading participants, this means a substantial increase in trading opportunities and flexibility, as well as more possibilities for investors in different time zones to participate.

How the new model divides trading sessions: Detailed explanation of two major trading periods in Eastern Time

Nasdaq’s “5X23” system divides the trading cycle into two main phases:

Day trading session from 4 a.m. to 8 p.m. Eastern Time, maintaining the current structure—comprising pre-market, regular, and after-hours trading segments. The traditional opening bell (9:30 a.m. ET) and closing bell (4:00 p.m.) will continue to be preserved as iconic market moments.

Night trading session begins at 9 p.m. ET and continues until 4 a.m. the next day. Notably, trades executed between 9 p.m. and midnight will be considered part of the next calendar day, which has important implications for cross-day arbitrage and risk management.

Reconstructing the trading cycle: New cycle starts on Sunday evening

Under the new system, the boundaries of the trading week will be redefined. Each trading week will officially start at 9 p.m. on Sunday (ET) and close at 8 p.m. on Friday (during the daytime session). This cycle division provides a smoother connection mechanism for market participants across different global time zones.

Once approved, this reform will significantly enhance market continuity and trading efficiency, signaling a move toward a more open and extended trading hours landscape for global stock markets.