A stop loss is a pre-set price where you exit a losing trade automatically, capping your loss before it grows. It’s the single most important risk tool a trader has — the mechanism that turns “how much could I lose?” from an open question into a fixed, known number you decided in advance.
Traders don’t blow up because they’re wrong. They blow up because they don’t have — or don’t honor — a stop.
Why pre-set exit rules beat emotion
The moment you’re in a trade, your judgment gets compromised. A losing position triggers hope — “it’ll come back” — and hope is how a small loss becomes an account-ending one. Setting your stop before you enter, when you’re calm and objective, removes the in-the-moment decision. The rule protects you from the version of you that panics.
Where to place a stop loss
A good stop sits at a level where your trade idea is proven wrong — below support for a long, above resistance for a short — not at a random dollar amount. Then you size the position so that hitting the stop only costs your planned risk, usually 1–2% of the account. The level defines where you’re wrong; position size defines what being wrong costs.
| Stop Type | How It Works |
|---|---|
| Fixed stop | Set level, exit if hit |
| Trailing stop | Moves up with price to lock gains |
| Structure stop | Placed beyond a key level |
For a step-by-step walkthrough of each method, read how to set a stop loss the right way.
Stop-market vs stop-limit orders
When you place a stop, your broker usually offers two order types. They behave very differently when price moves fast.
- Stop-market: once your stop price trades, the order becomes a market order and fills at the next available price. You get out, but in a fast move or a gap, the fill can be worse than your stop.
- Stop-limit: once your stop price trades, the order becomes a limit order. You won’t fill worse than your limit, but if price blows through it, you may not fill at all and you’re still in the trade.
For most traders, getting out matters more than the exact price, which is why stop-market orders are the common default for protective stops.
Your stop sets your position size
The stop comes first. Your size comes second. Decide where the idea is wrong, measure the distance from entry, then size the trade so a stop-out costs your fixed risk, your 1R.
That’s why a wide stop isn’t “riskier” if you size it correctly. It just means fewer shares. Our position sizing guide walks through the math, and reward-to-risk explained shows how the stop sets up your target.
5 stop loss mistakes to avoid
- Too tight: a stop inside normal price noise gets hit on moves that mean nothing.
- Moving it further away: once you widen a stop mid-trade, a planned 1R loss can become 2R or 3R.
- Right on a round number: obvious levels collect stops. Give yours a little room past the zone.
- Only in your head: a mental stop is easy to talk yourself out of. Place the real order.
- Ignoring gaps: a stop can’t protect you from an overnight gap past it. Size smaller into earnings and big news.
The MTC take: the exit is the trade
Everyone obsesses over entries. But your entry doesn’t control your outcome — your exit does. A pre-set stop is you making the hardest decision (when to admit you’re wrong) at the only time you can make it clearly: before money is on the line. Honor the stop every time, even when it stings, and no single trade can ever take you out of the game. That’s the whole edge.
