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The period at the beginning of the trading session officially designated by an exchange, during which all transactions are considered made "at the opening." Related: Close.


1. The beginning of a trading session on an exchange.

2. The first price of a security at the beginning of a trading day. In this sense, the opening is also called the opening price.


1. The beginning of a trading session.
2. The initial price at which a security trades for the day. Also called opening price.


The first transaction in each security or commodity when trading begins for the day occurs at what's known as its opening, or opening price.

Sometimes the opening price on one day is the same as the closing price the night before. But that's not always the case, especially with stocks or contracts that are traded in after-hours markets or when other factors affect the markets when the stock or commodity is not trading.

The opening also refers to the time that the market opens for trading or the time a particular instrument begins trading. For example, New York Stock Exchange (NYSE) opens at 9:30 ET. The first transaction in a single security may be at that time or at a later time.

References in periodicals archive ?
By taking X-rays of captured pregnant turtles, the scientists found that average egg size increased as the body size of adult female turtles increased, reflecting parallel increases in the size of the pelvic opening.
Perhaps, the scientists suggest, the structures surrounding, and therefore influencing, the pelvic opening are so important to mobility and other nonreproductive behavior that expansion of the opening to allow larger eggs has not had priority in terms of evolutionary changes for some species.
This anatomical combination challenges the long-standing idea that wide pelvic openings in the Homo genus evolved in response to brain expansion, allowing females to give birth to babies with relatively big heads, Kibii contends.