Open

Stock trading dictionary: meaning, example and how traders use it.

Last updated: October 17, 2026

Definition: The open, or opening price, is the price of a security's first trade when the regular trading session begins, at 9:30 a.m. Eastern for US stocks; it is one of the four OHLC values shown on bar and candlestick charts.

How the opening price is set

At the start of regular market hours, US exchanges do not simply take the first random trade. The NYSE and Nasdaq run opening auctions (Nasdaq calls it the Opening Cross) that collect buy and sell orders submitted before the opening bell and calculate a single price that matches the most shares. That auction price usually becomes the official open on the primary listing exchange.

Prices can move before 9:30 a.m. because of pre-market trading, but the official opening price reflects the auction at the start of the regular session. Data vendors sometimes differ slightly in which print they report as the open.

Opening gaps

A gap occurs when the open is meaningfully above the prior day's close (a gap up) or below it (a gap down). Gaps usually reflect news released while the market was closed, such as earnings reports, economic data, or developments overseas.

  • Breakaway gaps start new trends, often from a consolidation.
  • Exhaustion gaps appear late in a move and may soon reverse.
  • Common gaps are small and often fill within days.

Example of using the open

Suppose a stock closed at $80.00 and the company reports strong results after hours. The next morning, the opening auction prices the stock at $86.00, a 7.5% gap up. By midday the shares trade at $88.50, above both the open and the prior high, and they finish at $89.00. On a candlestick chart, this creates a tall body starting at $86.00, showing buyers stayed in control all day.

If instead the stock had opened at $86.00 but faded to close at $81.00, the candle would show heavy selling after the open, which many traders would interpret as weak follow-through despite the good news.

How traders use the open

Day traders watch the first minutes after the open, when volume and volatility are often highest. Some strategies trade a breakout above or below the opening range, such as the high and low of the first 15 or 30 minutes. Others compare the open with the close: a close above the open forms a bullish candle, a close below forms a bearish one.

Investors placing market orders before the open should note that the first prices of the day can be volatile and spreads can be wide. Limit orders give more control over the fill price, especially after news-driven gaps. Opening dynamics are a basic building block of day trading and short-term charting.

Frequently asked questions

What time does the US stock market open?

Regular trading on the NYSE and Nasdaq opens at 9:30 a.m. Eastern time on business days that are not market holidays.

Is the opening price the same as the previous close?

No. The open often differs from the previous close because news and pre-market orders change supply and demand overnight.

What is an opening gap?

It is a jump between the prior session's close and the next session's opening price, usually caused by news released while the market was closed.

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For information only, not investment advice. See the disclaimer.