What it means
The most common version is a stop-loss sell order placed below the price you paid. If the market falls to your stop price the order activates and your position is sold, converting a paper loss into a closed and known one before it can grow further.
Stops work in the opposite direction too. A buy stop placed above the current price is used either to enter a position when a share breaks through a level the trader considers significant, or to close a short sale before the loss on it widens.
The commercial value of a stop is discipline rather than cleverness. Deciding your exit before you enter forces you to size the position against a loss you have agreed to accept, and it removes the temptation to keep holding a falling asset in the hope that it turns around.
The critical detail is that a triggered stop usually becomes a market order, so you receive the next available price rather than your stop price. In a fast-moving or thinly traded market the fill can be well below the trigger, an effect known as slippage, and a price gap overnight can skip your level entirely.
Several variants exist to manage that risk. A stop-limit order becomes a limit order instead, protecting you from a terrible price but risking no execution at all, while a trailing stop moves upwards automatically as the price rises so that gains are progressively protected.
It also helps to know that stops rest with the broker or the exchange and can be visible in the order book, which is one reason clusters of stops just below round numbers sometimes get triggered together.
In practice
Real-world examples.
Example
A private investor holds an energy stock that has risen from $22 to $38 and sets a trailing stop 12% below the market price. The stop drifts upwards with the rally and eventually executes near $41, protecting most of the gain without any decision being made in the moment.
Example
A corporate treasurer running a small currency hedging book uses buy stops above key levels to limit losses on short positions. The desk's mandate requires every open position to carry a working stop, so no single overnight move can exceed the board's approved loss limit.
Example
A day trader places a stop-limit order to sell at a $27.00 stop with a $26.85 limit. The stock gaps straight to $25.90 on takeover news that collapses, no fill occurs because the price never returns to the limit, and the trader is left holding the position she intended to exit.
Think of it
“Stop order triggers when price hits a level-becomes a market order at that point.
Formula
Calculation
Loss on a triggered stop-loss = (Entry price - Actual fill price) x Number of shares
Position size = Maximum acceptable loss / (Entry price - Stop price)
An investor with a $200,000 portfolio buys 2,000 shares of an engineering company at $50.00, committing $100,000. She places a stop-loss sell order at $45.00 because that level sits below a support area on the chart.
Her planned risk is ($50.00 - $45.00) x 2,000 = $10,000, which is $10,000 / $200,000 = 5% of the portfolio. That is at the upper end of what she is willing to lose on one position, so she notes it as a maximum.
A profit warning arrives before the open and the shares gap lower. The stop triggers and fills at $44.80, so proceeds are 2,000 x $44.80 = $89,600 and the realised loss is $100,000 - $89,600 = $10,400. The $400 of slippage is the $0.20 shortfall on 2,000 shares. Working the formula the other way, if she had wanted to risk no more than $6,000 with the same $5.00 stop distance, she would have bought $6,000 / $5.00 = 1,200 shares instead.Case study
Seen in the real world.
Larkfield Capital is an invented boutique investment manager used here as an illustration. Its fictional equity book ran roughly forty positions, and the founder's rule was simple: no position without a stop, and no stop moved further away once set.
During one illustrative quarter a mid-cap holding fell steadily on weakening guidance, and the analyst covering it argued strongly for widening the stop because the sell-off looked overdone. The founder refused, the stop executed at a 9% loss, and the shares fell a further 34% over the next two months as a covenant breach emerged.
In the same illustrative period the discipline also cost the firm money: two positions were stopped out on brief market-wide falls and then recovered strongly without Larkfield on board. The invented founder's conclusion was that stops trade a series of small, tolerable costs for protection against the occasional loss large enough to threaten the fund, and that is a bargain worth accepting.
Watch out
Common mistakes.
- Assuming a stop order guarantees the stop price. It guarantees an attempt to trade once the level is touched, and the fill can be materially worse in a gap or a fast market.
- Setting stops at obvious round numbers just below the current price. Those levels attract clusters of orders and are more likely to be reached on ordinary intraday noise.
- Moving a stop further away when the position goes against you. That turns a defined risk into an open-ended one and defeats the entire purpose of placing the order.
Questions
People also ask.
What is the difference between a stop and a limit order?
A stop activates once a trigger price is touched and then trades at the market, while a limit order only ever trades at your specified price or better.
Should the stop distance be the same for every share?
No, a volatile small-cap needs a wider stop than a stable large-cap, and the position size should be adjusted so the money at risk stays consistent.
Do stops work outside trading hours?
Generally not, since most stops only operate during the exchange session, which is why an overnight gap can leave you filled well below your intended level.
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