The point at which an EOD order will close depends on the trading hours for your given market. If we take EOD orders on stocks, for example, the closing time will depend on the given exchange’s hours. Day orders on London Stock Exchange-listed shares will close at 4:30pm (UTC) each day, while day orders on Nasdaq or NYSE-listed shares will close at 9pm (UTC).
EODs are often contrasted with good-‘til-cancelled orders (GTC). While an EOD closes automatically at the close of trade on the same business day, GTC stays in the market until you cancel it, or it’s filled – whether that’s a day or a week after it’s opened.
You might choose to use an EOD instead of a GTC if you’re only looking to speculate on intra-day movements, and don’t want to monitor the position’s progress after the trading day has closed. But, if your EOD is left unfilled and you want to maintain it the next day, you’ll need to enter a new order in the morning, whereas a GTC order remains in place.