Day Order

A day order is an instruction to buy or sell a security that automatically cancels if it doesn't get filled by the end of that trading session. It's one of several "time in force" settings, which is just the label for how long an order stays active before it's either executed or withdrawn.

When you place an order with your broker, you're not just saying what to buy and at what price — you're also implicitly or explicitly saying how long that order should keep trying. A day order says "only today." If the price never reaches your limit, or the market never trades your order, it simply disappears when the exchange closes, and you'd need to re-enter it the next day if you still want it.

The nuance that trips people up is that most brokers default to day orders without making a big deal of it, so traders sometimes assume their order is "out there" indefinitely when it actually vanished hours ago after a quiet, uneventful close. This matters especially for limit orders placed far from the current price — you might set a buy limit well below the market expecting to catch a dip days later, only to find the order was gone after the first afternoon.

The alternative is a "good till canceled" (GTC) order, which stays live across multiple sessions until it fills or you cancel it yourself. Day orders and GTC orders are opposite ends of the same setting, and choosing between them is really a question of how long you want an unfilled instruction to keep waiting.