Each company trades at only one assigned post on the floor. Several companies may share a post, but a specific company's stock can be bought or sold only at its assigned post. This is to make sure trading can be tracked correctly. The trading day is frenetic, and all must guard against confusion. The floor brokers can trade with the specialists' help to find matches.
Timing is crucial, because a price can change at any time.
Each post has a computer display that shows the stocks traded, each stock's last sale price and the number of shares traded. This helps everyone keep track. Remember, prices can change by the second. This becomes part of the NYSE's permanent record. When the floor broker makes a trade as requested, she sends the trade details back to her home brokerage office.