The term, “Close” actually refers to the “Closing Price”. This is the last price wherein a stock trades within the context of a regular trading session. Regular trading sessions run from 9:30AM to 4:00PM Eastern Time for a great deal of U.S. Markets,.
Several markets offer after-hours trading with a number of financial publications while market data vendors make use of the last trade within the markets as the closing price for that specific trading day. What other markets use for the closing price for the day is the 4:00PM price. These markets display prices for after-hours trading separately. Trades that are administered after the specified closing trading time are tagged with the initial “T”. This will not affect the regular session closing price or the regular session high and low prices. One such market that uses this is the Nasdaq Stock Market.