Pre-market trading is buying and selling stocks before the regular US session opens at 9:30 AM New York time, at some brokers from as early as 4:00 AM.
A stock closed yesterday at $30.00. At 7:00 AM the company announces a large new customer, and the stock trades at $32.00 before the open. You want 100 shares but do not want to chase it, so you place a buy limit at $31.50.
If a pre-market trade reaches $31.50 or lower, you buy 100 shares for $3,150. If the price never comes back to $31.50, nothing fills. At 9:30 AM the regular session opens, and the stock may open above or below its pre-market price.
On JagSim, a stock limit order can fill before the open, from 4:00 AM to 9:30 AM New York time, if you tick "Fill during pre-market and after-hours" when you place it. Market and stop orders for stocks wait for the regular session: a market order placed before the open fills after 9:30 AM at the latest trade then, which can differ from the official opening price. JagSim sees fewer trades outside regular hours, for most stocks from about 8:00 AM, and a limit order fills only on a trade it sees. How trading works on JagSim.
Some brokers start it at 4:00 AM New York time and others later, such as 7:00 AM. It ends at the 9:30 AM open.
Company news, earnings and economic reports are often released before 9:30 AM, and traders react to them straight away.
No. The official opening price comes from the opening trade on the stock's main exchange at 9:30 AM, and it can be well away from the last pre-market trade.
Limit orders. Most brokers accept only limit orders outside regular hours, and a limit sets the worst price you will accept when there are few trades.
Last updated: October 2026
Educational only. Not investment advice. JagSim is a simulator, not a broker.
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