A market order is an instruction to buy or sell immediately at the best price currently available. It prioritizes speed and near-certain execution over price precision, so it almost always fills right away. The trade-off is that you accept whatever the current price is, which can shift slightly in fast-moving markets.
You place a market buy for 10 shares of AAPL quoted at $50. The order fills instantly at about $50, giving you the shares right away. In a fast market the fill might land at $50.05 instead of exactly $50, the price you glimpsed a moment earlier. If you need an exact price instead, you'd use a limit order and accept that it might not fill.
A market order is the first order type most people use because it's simple and fills fast. It matters because you trade control over price for near-certain execution. On a calm, heavily traded stock the fill usually lands where you expect; in a fast or thin name it can slip a little. Getting a feel for that gap on a paper-trading simulator, where nothing's at stake, is a low-pressure way to see how your orders actually behave. JagSim doesn't give buy or sell recommendations, price targets, or investment advice.
Using it on thin, fast-moving names. Placing a market order on a low-volume stock or during a big news swing can fill well away from the price you saw a second earlier. The quieter the name, the wider that gap tends to be.
Confusing it with a limit order. A market order takes whatever price is available right now, while a limit order names a price and may never fill. Mixing them up leads to surprise fills or orders that just sit there.
Treating the last quote as your fill price. The number on the screen is a snapshot, not a promise. Your real fill depends on the bid-ask spread and what's available at that exact instant.
In a liquid market it almost always fills right away because it accepts whatever price is available. Very thin, halted, or after-hours conditions are the main exceptions.
Quotes move constantly and the order fills against the current bid or ask, so in a fast market the executed price can land slightly off the number you clicked.
A market order prioritizes speed and fills at the best available price. A limit order prioritizes price and only fills at your set level or better, which means it might not fill at all.
Last updated: July 2026
Educational only. Not investment advice. JagSim is a simulator, not a broker.