Wall Street is about to stay open nearly all night

What this lesson covers

• What is actually changing in the US trading day
• Why it is happening now
• Why a quiet market can cost you more
• Why prices can move further overnight
• What it means if you are trading from Australia or Asia
• Five simple rules to keep in mind

The new trading day, in New York time

Nasdaq is adding a new overnight session. Put together with the sessions that already exist, the day looks like this.

That is 23 hours a day, Sunday night to Friday night, from 6 December 2026.

Why is this happening now?

Open is not the same as busy

0.9% of all US share trading happened overnight in August 2026. That is less than one share in every hundred.

You may also see the headline that overnight trading is up 359% in a year. That is true. But a tiny number that grows more than four times over is still a tiny number. Percentages need context.

Source: SEC staff data, September 2026.

A quiet market costs you more

Every share has two prices: what buyers will pay, and what sellers want. The difference is called the bid-ask spread. In this lesson it is simply the gap.

When the market is busy, the gap is tiny. When it is quiet, the gap gets wider.

Think of the money exchange counter at the airport. It is open at midnight, which is handy, but you pay for it in the rate.

3× Nasdaq research found that, for everyday investors, the cost of the gap overnight was around three times the daytime cost.

That research was done before the big exchanges joined in, so it may improve. We do not know yet. The point is not that overnight trading is bad. It is that not every trading hour is equal.

Source: Nasdaq research, 2025. Measured before the exchanges joined in.

The brake is looser at night

During the main session there is a brake. If a large company's share price moves too far from its recent price, trading can be paused or restricted. In the main session that level is around 5%. Overnight it is around 20%.

So a share can move four times as far before the brake comes on. Put that together with fewer buyers and sellers, and price moves can be sharper. It does not mean every share becomes volatile overnight. It means the market behaves differently.

Sources: SEC Investor Bulletin; Nasdaq Equity Trader Alert 2026-46.

New York's night is Asia's day

Local time of the new overnight session, December 2026.

Two things to remember, wherever you are. You can only trade this session if your broker offers it. And even if it is daytime for you, you are trading in America's quietest hours, so the gap may be wider.

Five simple rules

1. More hours is not a reason to trade more. If you invest for the long term, nothing changes for you.
2. If you trade at night, name your price. Use a limit order: the most you are willing to pay if buying, or the least you are willing to accept if selling.
3. Treat a night-time price as a rough guide. It can look very different when the full market opens.
4. Big company news will land while the market is open. The first reaction can be exaggerated.
5. Read your broker's warning. It covers the risks of trading outside normal hours.

Where to go next

New to shares altogether? Start with the first Stock Market Basics lesson. If you'd like to see ideas like these applied to real companies and real results, How Markets Think is where I write that up each week in plain English.