Stop-loss: admitting you're wrong in time

What a stop-loss is and why you need one

A stop-loss is an order that automatically closes your position if price falls to a set level. It answers, before you enter, the question "at what point do I admit I was wrong?"

A stop does three jobs:

1. It caps the loss. The maths of R:R and position size only works if losses stop at −1R.
2. It makes the decision in advance. It is hard to think clearly in front of a falling price. The stop is decided while you are calm.
3. It lets you size the trade. Without a stop you do not know the risk per share — and so you do not know how many shares to buy.

A trade without a stop is a trade without a plan. Failing to accept a small loss in time often turns it into a big one.

Where to put the stop: structure

The stop belongs at a logical place — the point where "my idea was wrong", not at a random percentage. The question is: where would price have to go for my reason to enter to disappear?

• just below a support zone;
• in an uptrend, below the last higher low (HL) (Market structure);
• after a breakout, below the level that was broken;
• in an order block or FVG setup, below the zone or the sweep wick.

On the chart the support zone is $48.90–49.50. A stop at $48.95, inside the zone, is a bad stop: an ordinary wick down to $48.60 took it out, and then price went up. The right stop is below the zone at $48.30. If the zone breaks, the idea really was wrong.

One more subtlety: don't put your stop exactly under a level everyone sees (equal lows, a round number). Stops cluster there and price often "sweeps" them (FVG and liquidity). Add a small buffer.

Buffer and distance: ATR

How far away should the stop be? ATR (average true range) answers that — how far a stock typically moves per period.

How ATR is calculated

For each candle, the true range is the largest of three numbers:

• high − low;
• |high − previous close|;
• |low − previous close|.

Example: yesterday's close $79.60, today's high $80.40, low $79.30 → max(1.10, 0.80, 0.30) = $1.10. With a gap: yesterday's close $50, today opens at $52 with a high of $52.50 and a low of $51.80 → max(0.70, 2.50, 1.80) = $2.50. ATR(14) is the average of the last 14 true ranges. Charting platforms have it as a ready-made indicator.

A worked example

• Entry $80, last low $78, ATR(14) = $1.20.
• Too tight: $79.40 — only 0.5 ATR below entry. If the stock moves $1.20 a day, this stop gets hit by an ordinary daily swing.
• Structure + ATR buffer: $78 − 0.5 × $1.20 = $77.40. Risk per share $2.60.
• A pure ATR stop as a cross-check: 2 ATR below entry → $80 − $2.40 = $77.60. The two methods agree closely — a good sign.
• Size: account $10,000, risk 1% = $100 → $100 ÷ $2.60 ≈ 38.5 → 38 shares (position $3,040, risk $98.80).

The usual approach is to place the stop at structure and check the distance with ATR: a stop closer than 1 ATR from entry often gets caught by noise. Many traders use 1.5–3 ATR on a daily chart, but that is not a law — it depends on the stock and the timeframe.