Stop and stop-limit orders

Market and limit orders act on the current price. Stop orders wait for a future price. They are the tool you will use to cut losses automatically, and they are also the tool that most often surprises beginners with a fill they did not expect. This lesson explains both faces.

The stop order

A stop order is a sleeping order. It does nothing until the market trades at (or through) a price you choose, the stop price or trigger. When that happens, it wakes up and becomes a market order.

• A sell stop is placed below the current price. When the price falls to the stop, it sells at market. This is the classic protective "stop-loss".
• A buy stop is placed above the current price. When the price rises to the stop, it buys at market. Used to enter on a breakout, or to close a short position.

Example: you own a stock at 50.00. You place a sell stop at 47.00. The stock drifts around 49 to 51 for a week; nothing happens. Then one morning it drops. The moment a trade prints at 47.00 or below, your order becomes a market sell and fills at the next available bid.

Note the last sentence. The stop does not promise you 47.00. It promises to try to sell once 47.00 is reached. If the next bid is 46.95, that is your fill. If the stock gapped overnight from 49 to 42 on bad news, your stop triggers at the open and fills around 42. You lost 8, not 3. Stops limit losses in normal conditions; they do not limit them in gaps.

Why stops are still worth using

Because the alternative, "I will watch it and get out manually", fails for predictable human reasons: you are asleep, at work, in a meeting, or simply unwilling to admit you were wrong. A stop turns the decision you made calmly, before the trade, into an action that happens without your emotions in the room. For most beginners the biggest losses are not from gaps; they are from not having a stop at all and letting a 3% loss become a 30% one.

Where you put the stop, and how much you risk per trade, is the subject of the Risk Management course. For now, the mechanics.

The stop-limit order

A stop-limit order also sleeps until the stop price is hit. But when it wakes up, it becomes a limit order rather than a market order. You set two prices:

• Stop price: the trigger.
• Limit price: the worst price you will accept once triggered.

Sell stop-limit, stop 47.00, limit 46.50: when 47.00 trades, a sell limit at 46.50 is placed. It fills at 46.50 or better. If the market blows straight through 46.50 without filling you, you are still in the position, riding it down with an order that will never execute.

That is the trade-off. A stop-limit protects you from a terrible fill; it does not protect you from staying in a terrible trade.

Which to use

For a protective stop-loss, most traders prefer the plain stop, because the whole point is to be out. Accepting a slightly worse price beats holding a collapsing position. The exception is very thin products where a market order could fill absurdly far away; there, a stop-limit with the limit set generously wide (say, 2-3% below the stop) gives you most of the protection with a floor against a flash-crash fill.

For a breakout entry (buy stop above resistance), a stop-limit is often better. If the stock explodes through your level on news, you probably do not want to chase it 5% higher; a limit a little above the stop lets you skip the trade if it runs away.

Stop-order traps

Trigger rules differ. Some brokers trigger on the last trade, some on the bid or ask, some let you choose. In a wide-spread stock this matters: a sell stop triggered by the ask fires later than one triggered by the bid. Read your broker's documentation once.

Stops are visible in some markets. On a centralized futures exchange, stop orders resting at the exchange are not displayed, but your broker may hold them on their server instead, which is fine too. The folklore that "market makers hunt your stop" is mostly exaggerated in liquid markets; what actually happens is that many traders cluster stops at the same obvious levels (just below round numbers, just below the recent low), so when price approaches those levels, a wave of market sells hits, which pushes price further. You get "hunted" by the crowd's collective predictability, not by a villain. Placing stops at slightly less obvious levels helps.

Stops do not work when the market is closed. A stop on a stock does not trigger pre-market unless you specifically enable extended-hours triggering, and most brokers do not allow that. Overnight gaps go straight past it.

A stop in a thin option is dangerous. Option prices jump around; a stop at 0.80 on an option quoted 0.75 x 0.95 can trigger on noise and fill at 0.75. Many traders manage option risk by the price of the underlying instead of a stop on the option itself.

Trailing stops are stops that move with the price: a sell stop set "3% below the highest price since entry" ratchets up as the stock rises and never moves down. Useful for letting winners run; just remember every trailing stop is still a market order when it fires.

Key idea: A stop order guarantees that you will try to exit once a price is hit; it does not guarantee the price. A stop-limit guarantees a price but not an exit. Choose based on which failure you can live with.

Try it: On a paper account, buy a small position in a liquid stock and immediately place a sell stop 2% below your entry. Leave it overnight. In the morning, check: did it trigger? At what price? Was that what you expected? Do the same with a stop-limit. Notice how much calmer you feel about the position with the order resting.

Recap

• A stop order sleeps until the stop price trades, then becomes a market order.
• Sell stops below the price protect longs; buy stops above the price enter breakouts or close shorts.
• Stops do not protect against gaps; they fill at the next available price after the trigger.
• A stop-limit becomes a limit order when triggered: price protection, no execution guarantee.
• Use plain stops for protective exits, stop-limits for breakout entries and thin products with a wide limit.