Wall Street is going 23×5: What it means for Asian investors

If you own and trade U.S. shares from this side of the world, you know the routine. The opening bell rings at 9:30pm or 10:30pm (UTC+8) (depending on U.S. daylight saving time) and closes at 5am. Anything that matters happens while you sleep, and you can only react in the night. By then, the news may have already moved the stock hours earlier. But from 6 December, that changes.

The U.S. market runs a full trading session from 10am to 5pm our time, right through the middle of your working day. So, you might be able to buy Apple stock during your lunch break at the year-end. In this article, we will discuss in depth what’s changing, what we can trade, why this matters, and what the catch is.

What’s changing, and when

Three exchanges are moving to 23 hours a day, five days a week, closing just for an hour daily for maintenance. All three are targeting the same date:

• NYSE Arca – initial extended-hours approval in February 2025; 23-hour framework updated in May 2026; targeting 6 December
• Nasdaq – SEC approved April 2026; launching 6 December
• Cboe EDGX – EC approved May 2026; launching 6 December

Overnight trading isn’t entirely new. Investors have already been able to trade U.S. stocks through alternative trading systems, such as Blue Ocean ATS (similar to the overnight trading already offered by apps like moomoo and Tiger Brokers). What has been missing is the official consolidated market-data infrastructure: market-wide quotes and trades, including the National Best Bid and Offer (NBBO). It is basically the share price feed, the system that collects quotes from every venue and publishes the official best price for a stock. It was built around a trading day that ended at 8 p.m. New York time, so it simply switched off overnight.

That changes on 6 December, when the Securities Information Processors are scheduled to begin operating 23 hours a day, allowing exchanges with approved overnight-trading rules to extend trading into the overnight session. That also means investors will have an official consolidated NBBO throughout the overnight session.

What can be traded?

All listed National Market System (NMS) stocks, announced by Cboe EDGX and NYSE Arca, which broadly cover U.S.-listed shares and exchange-traded products, including ETFs and exchange-listed ADRs, will be eligible for the new overnight sessions. This is much broader than today’s overnight ATSs, which typically offer only a few hundred popular securities. OTC stocks and traditional mutual funds are not included, while options operate under separate exchange rules and trading schedules. Your broker may still restrict which securities it allows customers to trade.

Below are the trading times in UTC+8:

*During U.S. standard time. All SGT/MYT times shift one hour earlier during U.S. daylight saving time.

Why this matters

• You are not stuck waiting all day. Say a company you hold reports bad results, or some fundamentally bad news happened overnight while you are asleep. You wake up to the news, but by the time you have had breakfast and got to your desk, it is too late: the U.S. market closed at 5am. Nothing reopens until 5pm, and the main session not until 10.30pm. That is a full working day holding a position you can do nothing about. From December, that gap is exactly when the market is open.
• Price transparency. Overnight trading currently happens on scattered private venues that don’t share prices. You see whatever your broker’s venue shows and have no way to verify it elsewhere. From December, there is a single published price, like during the day.
• Every stock, not a shortlist. Overnight trading today covers only a few hundred popular names. From 6 December onwards, the exchanges carry essentially every U.S.-listed stock and ETF, though your broker may still keep its own shorter list.
• Trades settle through the main system. Overnight trades will clear through the same central infrastructure as daytime trades, rather than a small operator’s own arrangement, which could reduce the chance of a breakdown similar to that of August 2024.

So what’s the catch?

• Stop-loss may not be available. The new overnight sessions are built around limit orders rather than market orders, and stop orders are generally unavailable during these sessions. That matters if you normally rely on a stop-loss to exit automatically when a stock falls sharply.
• Low liquidity. Based on 2025 data from Nasdaq, overnight trading accounts for only 0.2% of total U.S. equity market volume, with liquidity much thinner than during regular hours. This can mean wider gaps between buying and selling prices, while even a modest order may move the price more than you’d expect.
• Wider safety rails. During regular trading hours, most U.S. stocks above USD 3 are generally subject to ±5% or ±10% Limit Up–Limit Down bands around a rolling reference price. From 6 December, overnight trading will instead use much wider bands of roughly ±20% for most stocks. Unlike the daytime system, hitting the overnight band does not automatically trigger a five-minute trading pause, though exchanges may halt trading for the remainder of the overnight session.
• The regular session still rules. Even with overnight trading, the traditional 4 p.m. New York close remains the official closing price. NYSE Arca will continue to determine its official closing price through the 4 p.m. Core Closing Auction, while Nasdaq’s Closing Cross will also remain at 4 p.m. Overnight trading extends the hours during which investors can trade, but it does not replace the importance of the regular-session close.

Could 23×5 encourage overtrading?

I believe it’s possible. The closing bell used to create a natural friction; once the market shut, investors had to wait.

For us, as Asian investors, a 10am-5pm (UTC +8) overnight session is much easier to access than a 2 a.m. market. That convenience could make impulsive trading more tempting. Now, when we wake up to the bad news, we have the whole time to process, ponder, then make the decision.

But more trading hours do not necessarily mean more opportunities. Overnight liquidity is thinner, and some risk-management tools may be unavailable. Ultimately, trading frequency is still a choice; an open market does not require you to act.

The fifth person

If you hold ETFs for the long term, little changes for you. If you trade actively, however, you’re getting a genuinely useful new window, which was driven partly by growing demand from investors in Asia. Just remember what it is: a thinner market with fewer tools than the regular session.

And the framework is still evolving. At an SEC roundtable in September, Commissioner Hester Peirce asked how investor protection should work in an overnight market when much of the demand may come from retail investors. With the new market infrastructure due to go live on 6 December, regulators and the industry are still discussing what additional protections may be needed.