Simple definition
A stop order is an instruction to your broker that turns into a market order once an investment hits a set trigger price. It's often used to limit losses by selling automatically if a price falls. Think of it like a tripwire: nothing happens until the price crosses your line, then the order fires.
Why it matters
A stop order can help you cap a loss or protect a gain without watching the market all day. But it's not a guarantee: once triggered, it becomes a market order that fills at the next available price, which in a fast-moving or thinly traded market can be worse than your trigger.
Real-life example
Say you own a stock at $100 and set a stop order to sell at $90. If the price drops to $90, the order becomes a market order and sells at roughly that level — though in a fast drop it might fill lower. These are rounded, hypothetical numbers, not a recommendation.
Common mistakes
- Assuming a stop order always sells at your exact trigger price, when it fills at the next available price.
- Setting the trigger so close to the current price that normal swings sell you out early.
- Forgetting that a gap down overnight can trigger a sale far below your intended price.
- Confusing a stop order with a stop-limit order, which may not fill at all in a fast move.
Pro tips
- Understand a stop order becomes a market order once triggered, so the fill price isn't guaranteed.
- Give the trigger enough room that ordinary price swings don't sell you out unnecessarily.
- Learn how a stop-limit order differs before choosing between the two.
- Use stop orders as one tool, not a substitute for a thought-out plan.
Related Money Dictionary terms
- Market OrderAn instruction to buy or sell an investment right away at the best price currently available.
- Limit OrderAn instruction to buy or sell only at a specific price or better, giving you control over the price you get.
- Stop-Limit OrderAn order combining a trigger price with a price limit, giving you more control than a plain stop order.
- Brokerage AccountAn account you open with an investment firm to buy and sell stocks, bonds, funds, and other investments.
- VolatilityHow sharply and often an investment's price swings up and down over a given period.
- StockA share of ownership in a company that you can buy and sell, giving you a small stake in its profits and growth.
Frequently asked questions
What's the difference between a stop order and a limit order?
A limit order sets the specific price you'll accept and only fills at that price or better. A stop order sits dormant until the price hits your trigger, then turns into a market order that fills at whatever price is available next. A stop controls when you act; a limit controls the price.
Does a stop order guarantee I won't lose more than planned?
No. Once triggered, a stop order becomes a market order and fills at the next available price, which can be worse than your trigger in a fast or thinly traded market. If a stock gaps down overnight, your sale could execute well below the level you set. It limits, but doesn't guarantee, your loss.
What is a stop-limit order and how is it different?
A stop-limit order combines a trigger with a price limit: once triggered, it becomes a limit order rather than a market order. That protects you from a bad fill price, but it can also fail to execute at all if the price moves past your limit too quickly. Each type trades one risk for another.
Knowing what Stop Order means is knowledge — the first half. A brick gets placed when you act on it: Before using stop orders, read investor.gov's explanation of order types and confirm how your broker handles a triggered stop..
Sources & references
More in Investing
Plain-English education — not personalized legal, tax, or investment advice.