What is the difference between SL and SL-M?

An SL order becomes a limit order at your chosen price when triggered, so it may not fill. An SL-M order becomes a market order, so it usually fills but at an uncertain price.

Can a stop-loss fail?

Yes. If the price gaps past your stop, it fills at the next available price or, for an SL limit order, may not fill at all.

What is a trailing stop-loss?

It is a stop that moves up with the price in a long trade (or down in a short trade) and never moves back, so it locks in part of a favourable move.

Should I hold my stop in my head instead?

A mental stop gives flexibility but relies on discipline and on you watching the screen. A placed order executes even if you are away.

What is a stop-loss?

Updated 11 October 2026

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A stop-loss is a price at which you plan to exit a trade that is going against you. It turns a vague hope ("it will come back") into a fixed decision made before emotions take over. You can keep it in your head, but most traders place it as an order with their broker so it triggers automatically.

Order types in India

SL (stop-loss limit)

You enter two prices: a trigger price and a limit price. When the market trades at or through the trigger, your order goes to the exchange as a limit order at your limit price. For a long position you might set trigger ₹490 and limit ₹488. Your sell will fill only at ₹488 or better.

The benefit is price control. The risk is that in a fast fall, price can drop through both ₹490 and ₹488 without your order filling, leaving you still holding the stock as it keeps falling.

SL-M (stop-loss market)

You enter only a trigger price. When it is hit, a market order goes to the exchange and fills at the best available price. You are almost sure to get out, but you do not control the price. In a thin or fast market, the fill can be well below your trigger. Some brokers do not allow SL-M orders for options contracts, so check what your platform offers.

Trailing stop-loss

A trailing stop moves in your favour as price moves in your favour, and never moves back. For example, you buy at ₹500 with a stop ₹10 below at ₹490. If the stock rises to ₹520, the stop trails up to ₹510. If it then falls, you exit around ₹510 instead of ₹490. Some platforms offer this as an order type; many traders simply move the stop by hand at the end of each day or each candle.

Where to place a stop

A stop is most useful when it sits where your trade idea is clearly wrong. Common reference points are below a recent swing low, beyond a support or resistance zone, or a multiple of the average daily range. Placing it at a round number just because the loss "feels okay" often leads to stops that are hit by normal noise.

Once you know where the stop is, the distance from entry decides your quantity. That is the job of position sizing and the position size calculator. The stop also sets the risk side of your risk-reward ratio.

Gaps can skip a stop

A stop is a plan, not a guarantee. The NSE and BSE cash session runs from 9:15 am to 3:30 pm. News after the close, overnight global moves or results can make a stock open far from its previous close. If it opens below your stop, there is no trade at your stop price, so you get the next available price.

Worked example

You hold 300 shares of Stock ABC bought at ₹500, with an SL-M sell order triggered at ₹490.

Planned risk = (₹500 − ₹490) × 300 = ₹3,000

The stock closes at ₹498. Overnight, bad news comes out, and it opens at ₹470. Your trigger is hit at the open and the order fills near ₹470.

Actual loss = (₹500 − ₹470) × 300 = ₹9,000
That is three times the planned loss, before costs.

Had you used an SL order with a limit of ₹488, the order would sit unfilled because the stock is trading far below ₹488. You would still hold the shares and would need to decide what to do. Neither order type protects you from a gap; they only decide how you exit after it.

Other things that can go wrong

Circuit limits. If a stock hits its lower price band, there may be no buyers at all, and a sell order cannot fill until trading resumes.
Order validity. Day orders expire at the close. If you hold overnight, you may need to place the stop again the next morning, depending on your broker's options.
Intraday square-off. Intraday positions are closed by the broker near the end of the day anyway. See intraday vs delivery.
Moving the stop away. The most common failure is human: shifting a stop further away because you do not want to take the loss.

Making stops more realistic

Because gaps happen, some traders size positions assuming a worse fill than the stop, especially when holding overnight or through results. Others avoid holding leveraged positions over events. In derivatives, a gap combined with leverage can produce a loss larger than the margin you put up.

Risk reminder

A stop-loss limits damage on most days, not every day. SEBI's studies (2023 and 2025) found about 9 in 10 individual F&O traders lost money in the years studied (SEBI). Decide your stop before you enter, size the trade from it, and assume that once in a while the market will skip it.

Questions people ask

What is the difference between SL and SL-M?: An SL order becomes a limit order at your chosen price when triggered, so it may not fill. An SL-M order becomes a market order, so it usually fills but at an uncertain price.
Can a stop-loss fail?: Yes. If the price gaps past your stop, it fills at the next available price or, for an SL limit order, may not fill at all.
What is a trailing stop-loss?: It is a stop that moves up with the price in a long trade (or down in a short trade) and never moves back, so it locks in part of a favourable move.
Should I hold my stop in my head instead?: A mental stop gives flexibility but relies on discipline and on you watching the screen. A placed order executes even if you are away.