What Is a Stop-Loss? Managing Risk on a Trade

A stop-loss is a pre-set order that activates on its own when a stock hits a price you choose. It is one of the most common tools people use to define, in advance, how much they are willing to risk on a trade.

How a stop-loss works

A stop-loss order sits dormant until the market reaches your chosen stop price. At that point it triggers automatically and submits an order to exit the position. The idea is to remove emotion from the decision: you decide the exit level while you are calm, and the order carries it out without you having to watch the screen.

Stop-market vs. stop-limit

The two main types differ in what happens after the trigger, and the difference matters:

• Stop-market: once triggered, it becomes a market order and fills at the next available price. It almost always executes, but in a fast drop the fill can come well below your stop price.
• Stop-limit: once triggered, it becomes a limit order at a price you set. It protects you from a terrible fill, but if the price gaps straight past your limit, it may not fill at all — leaving you still holding the position.

The gap risk

Stops are triggered by trading during market hours. If bad news breaks overnight and a stock opens far below your stop, a stop-market order fills at that lower opening price, not your stop level. This gap risk is the single most misunderstood limit of stop-loss orders — they cannot protect against a price that jumps over your level while the market is closed.

Where people commonly place them

These are descriptions of common approaches, not advice on what to do:

• Below a support level. Some place a stop just under a support zone, on the reasoning that a break below it changes the picture.
• A fixed percentage. A set distance, such as 8–10% below the entry, keeps the risk consistent trade to trade.
• Based on volatility. On a stock with high volatility, a stop placed too close can be triggered by normal daily swings rather than a real change in trend.

Trailing stops

A trailing stop follows the price up. Set at, say, 10% below the market, it rises as the stock rises but never falls, so it can lock in gains as a position moves in your favor while still exiting if the price turns down by your chosen amount.

The trade-off

A stop set too tight can eject you from a position on ordinary noise, right before it recovers. A stop set too loose exposes you to a larger loss. There is no perfect setting — it is a balance between giving a trade room to breathe and defining a loss you can accept. This is the heart of broader risk management.

The bottom line

A stop-loss automates an exit at a price you decide ahead of time, which is why it is a cornerstone of disciplined risk control. But it is a tool with real limits — gaps, slippage, and noise can all interfere — so it manages risk rather than eliminating it. Understanding exactly what it can and cannot do is what makes it useful.