Definition
Stop Loss
A stop loss is a pre-set order that triggers an automatic sell (or buy, for shorts) once a security hits a chosen price, capping your loss without you having to watch the screen.
A stop loss is risk management on autopilot. You decide in advance the worst loss you are willing to accept on a trade, place the order, and the system acts for you if the price reaches that level.
How it works
Say you buy a stock on NSE at ₹500 and decide you will not risk more than 10%. You place a stop loss at ₹450. If the price falls to ₹450, the order activates and sells your shares, stopping further bleeding.
Indian brokers offer two common variants. A Stop Loss Market (SL-M) order sells at the best available price the moment the trigger hits, guaranteeing execution but not price. A Stop Loss Limit (SL) order has both a trigger and a limit price, guaranteeing price but risking no fill if the stock gaps past your limit. Many trades also use a bracket or GTT (Good Till Triggered) order so the stop persists across days.
Why it matters
The biggest enemy of an investor is not the market, it is emotion. A pre-set stop removes the temptation to "give it one more day" while a position spirals. It enforces discipline and keeps any single trade from blowing up your capital.
Common mistakes
Beware of gap-downs. If a stock hits a 20% lower circuit or opens far below your trigger after bad news, an SL-M can fill well below your intended level, and an SL-limit may not fill at all.
Avoid placing stops too tight. Normal intraday noise can knock you out of an otherwise good position, a frustration traders call getting "stop hunted". Set the stop based on the stock's volatility and your conviction, not a round number.
Finally, stops suit traders more than long-term investors. If you are SIP-ing into an index fund for retirement, a stop loss is the wrong tool; you would simply be selling quality assets cheap during a dip. Use stops where you are taking directional, leveraged, or short-term bets.
Plain-English explainer from The Dispatch Investors Encyclopedia. General information, not financial advice.