Ask any experienced investor what separates survivors from those who blow up, and many give the same one-word answer: the stop-loss. It's the simplest risk rule there is — and the most ignored. This is for learning only.
What a stop-loss is
A stop-loss is a price, decided in advance, at which you will exit a position to cap your loss. Buy a share at ₹100, set a stop at ₹92, and if it falls there you're out — your loss is limited to 8%, no arguing with yourself in the heat of the moment.
Why big losses are so dangerous
Here's the maths most people never see: a loss and the gain needed to recover it are not equal. The deeper the hole, the harder it is to climb out.
| If you lose | You need this gain just to break even |
|---|---|
| 10% | 11% |
| 25% | 33% |
| 50% | 100% |
| 75% | 300% |
| 90% | 900% |
A 10% loss is a small bruise. A 50% loss means your money must double just to get back to where it started.
Why a 75% loss needs a 300% gain — the maths
That "300%" looks strange, so here is the simple arithmetic behind it.
Say you start with ₹100 and lose 75%. You are left with just ₹25. To get back to your original ₹100, that ₹25 now has to grow back to ₹100 — and ₹25 growing to ₹100 is four times your money, which is a 300% gain. You lost 75% in one fall, but you need a 300% rise to undo it.
The rule behind the whole table is one small formula:
gain needed (%) = loss ÷ (100 − loss) × 100
Notice how the gain needed explodes as the loss deepens — it rises far faster than the loss itself. That is the whole reason to keep every loss small: a shallow hole is easy to climb out of, but a deep one can be almost impossible. Cutting losses small matters far more than being right often.
How big should your stop-loss be?
There is no single "right" distance. Too tight and normal day-to-day wiggles throw you out of a good position; too loose and you lose more than you needed to. Three things should decide how far below your price the stop sits.
1. How volatile the stock is. A jumpy, high-volatility stock can move 4–5% on an ordinary day. Put a tight 2% stop on it and you'll be "stopped out" by normal noise again and again — even when nothing is actually wrong. Such stocks need a wider (deeper) stop so they have room to breathe. A calm, low-volatility stock that barely moves 1% a day can take a tighter stop, because a 2–3% fall there already signals that something has changed. In short: match the stop to how much the stock normally swings. (To keep your rupee risk the same, a wider stop simply means taking a smaller position — see what is position sizing.)
2. How much leverage you're using. Leverage — borrowed money, or F&O — magnifies every move, so a small fall in the stock becomes a big loss on your money. Leveraged, quick-trade positions are built for fast, small wins, so they need a tight, small stop-loss: you simply can't afford to let a leveraged trade drift against you. The more leverage, the tighter and stricter the stop. (And remember — SEBI's data shows most leveraged F&O traders lose money; leverage cuts both ways, hard.)
3. How long you plan to hold. If you're a long-term investor holding for months, use a wider stop — you want to ride out the normal ups and downs without being shaken out by a passing dip. If you're taking a short-term or leveraged position aiming for a quick gain, use a tight stop — the whole point is to exit fast if it doesn't work.
Put it all together and the pattern is simple: wider stops for calm, long-held positions; tighter stops for volatile, leveraged, short-term ones. The stop should fit the stock and the trade — not be the same number every time.
The discipline part
A stop-loss only works if you actually honour it. The hardest moment in investing is admitting a position isn't working and exiting while the loss is small. SEBI's own studies have shown that around 9 in 10 individual F&O traders lose money — and a big reason is letting small losses snowball because they refuse to exit.
The point of a stop-loss isn't to be right. It's to make sure that when you're wrong, you're only a little wrong. Protect your capital first; the profits can wait. For more, read intraday trading vs positional investing.
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