What it is:
Opening bell refers to the beginning of the trading day on an exchange. However, in the United States, only the New York Stock Exchange (NYSE) rings an actual bell every day.
How it works/Example:
At 9:30 A.M. on every trading day, four bells -- one in each of the NYSE's trading areas -- ring simultaneously to signal the start of trading. A Chinese gong was used before the exchange brought in brass bells in 1903.
Each opening bell is 18 inches in diameter and was manufactured by the G. S. Edwards Company of Norwalk, CT. Interestingly, the NYSE found a larger, older bell in a crawlspace above the trading floor when the NYSE was refurbishing the original bells in the 1980s. This larger bell is now a backup bell and sits on a platform above the trading floor.
Why it matters:
The opening bell signifies the beginning of the trading day on an exchange.
A variety of people -- famous, infamous, and unknowns -- have had the privilege of ringing the opening bell (which actually involves pressing a buzzer) since 1956, and it is one of the most widely watched daily events in the world. The Opening Bell and The Closing Bell are service marks of the New York Stock Exchange.