What Is a Stop-Loss Order? (Day Trading Glossary)

A stop-loss order is an instruction you give your broker to automatically sell a stock if its price falls to a level you choose, so your loss is capped. It's the tool traders use to decide, in advance, how much they're willing to lose on a position.

You set the price. The broker does the selling for you if it gets hit.

How a stop-loss order works

First you pick a "stop price" below where the stock is trading. If the stock drops to or below that price, your stop-loss turns into a market order, and the broker sells your shares at the next available price.

A simple example: you buy a stock at $100 and set a stop-loss at $90. If the price falls to $90, the order fires and your shares are sold, capping your loss at roughly $10 a share. You don't have to be watching the screen for it to work.

The risks you should know

A stop-loss limits your loss, but it doesn't guarantee the exact price you'll get. Two things can widen the gap.

Slippage. When your stop triggers, it becomes a market order that fills at the best available price. In a fast drop, that price can be lower than your stop. You set $90, but a violent move might fill you at $89.40.

Gapping. If a stock closes at $100 and reopens the next morning at $70 on bad news, your $90 stop triggers on the way down and fills near $70, not $90. The stop can only act once trading actually happens at that price.

A stop-loss caps the size of a normal loss. A big, fast move can still get through it.

Stop-loss vs stop-limit

There's a related order worth knowing. A stop-limit order adds a limit price, so it won't sell below a number you set. That protects you from bad slippage, but it comes with a catch: if the price blows straight past your limit, the order may not fill at all, and you're left holding the stock. A plain stop-loss trades price certainty for the certainty of getting out.

How I use stops

For the fast small-caps I trade, the stop is the most important part of the trade, and I set it before I ever click buy. My stop usually sits a cent or two under VWAP or the 90 EMA, right under the level I'm leaning on. That tiny risk is what lets a small win pay for several small losses.

Two rules keep me honest. I never move a stop wider to avoid taking the loss, and I never cut my planned risk early out of fear either. The level I picked is the level.

The thin, fast stocks I trade are exactly where slippage and gaps hit hardest, so a resting stop-loss order can fill well below your price. I treat my stop as a pre-planned price to get out at fast, and I manage it closely rather than setting it and walking away. The habit that matters is deciding your exit before you enter, which is the core of my method.

Frequently asked questions

Are stop-losses a good idea?

For most traders, yes, because a stop-loss forces you to decide your risk before emotion takes over. The catch is that it caps a normal loss, not a violent one, since slippage and gaps can fill you below your stop. It's a discipline tool, and it works best paired with position sizing and a level that actually makes sense on the chart.

Why would you use a stop-loss order?

To limit how much you can lose on a trade and to take the decision out of the heat of the moment. Instead of freezing when a stock drops, you've already told your broker where to sell. It also frees you from watching every tick, since the order sits and waits for its price.

What are the downsides of a stop-loss order?

The main ones are slippage and gapping, where you fill below your intended price in a fast or overnight move. A stop set too tight can also get "shaken out" by normal wobble, selling you right before the stock recovers. Choosing a stop level with a bit of room, tied to real support, helps avoid that.

What is the 7% stop-loss rule?

It's a guideline some longer-term investors follow: sell a stock if it falls about 7% to 8% below your purchase price, to keep any single loss small. It's an investing rule of thumb, not an intraday day-trading rule, and active traders usually set their stop against a chart level instead of a fixed percentage.

This content is for educational purposes only and is not financial advice. Trading involves significant risk and may not be suitable for all traders.