Position Sizing

Stop-Loss and Risk-Reward Ratio

Position sizing tells you how much to risk. Stop-loss and risk-reward ratio tell you exactly where that risk starts and ends, and whether the trade is even worth taking in the first place. Together, they're what turn "I think this will go up" into a plan with defined boundaries on both sides.

What a Stop-Loss Actually Does

A stop-loss is a predetermined price at which you exit a trade if it moves against you — placed before emotion has a chance to interfere. It's not a prediction that the trade will fail; it's an admission that you don't know for certain it will succeed, and a way to cap the damage if it doesn't.

For example: you buy a stock at ₹500, expecting it to move up. You set a stop-loss at ₹480. If the price falls to ₹480, your position closes automatically — you lose ₹20 per share and walk away, instead of watching it potentially fall to ₹450 or lower while hoping for a reversal.

Risk-Reward Ratio: Is the Trade Worth Taking?

Risk-reward ratio compares how much you stand to lose (distance to your stop-loss) against how much you stand to gain (distance to your target). It's calculated before you enter the trade, and it's one of the fastest ways to filter out weak setups before you commit any capital.

The formula: Risk-Reward Ratio = (Entry Price − Stop-Loss Price) : (Target Price − Entry Price)

For example: entry at ₹500, stop-loss at ₹480 (₹20 risk), target at ₹560 (₹60 reward). That's a 1:3 risk-reward ratio — you're risking ₹20 to potentially make ₹60. A trade risking ₹40 to make ₹40 would be a 1:1 ratio — a much weaker setup, even if it "feels" similarly likely to work.

Why a Favorable Ratio Matters More Than Win Rate

A trader doesn't need to be right most of the time to be profitable — they need their wins to outweigh their losses over time. A strong risk-reward ratio means you can be wrong more often than you're right and still come out ahead.

Risk-Reward Ratio	Win Rate Needed to Break Even
1:1	Above 50%
1:2	Above ~33%
1:3	Above 25%

At a 1:3 ratio, a trader who's right just 30% of the time can still be solidly profitable overall — which is why professional traders obsess over risk-reward setups, not just "how often am I right."

Types of Stop-Loss Placement

• Fixed percentage/points: A stop-loss set at a fixed distance from entry (e.g., 2% below) — simple, but ignores the stock's own volatility or chart structure.
• Technical stop-loss: Placed just below a support level or a recent swing low — the stop-loss reflects where the trade idea itself would actually be proven wrong.
• Volatility-based (ATR): Set as a multiple of the stock's Average True Range, adapting automatically to how much a stock typically moves day to day.
• Trailing stop-loss: Moves up as the price moves in your favor, locking in gains progressively while still giving the trade room to run.

Common Mistakes to Avoid

• Moving the stop-loss further away mid-trade: Shifting the stop-loss to "give the trade more room" once it's already moving against you defeats its entire purpose — it turns a planned small loss into an unplanned large one.
• Setting a stop-loss too tight for normal price noise: A stop-loss placed inside a stock's normal daily fluctuation range gets triggered by routine noise, not by the trade thesis actually failing — leading to repeated small losses on setups that may have otherwise worked.
• Taking trades with a poor risk-reward ratio because the setup "looks good": A visually appealing chart pattern doesn't matter if the numbers don't work — a 1:1 or worse ratio needs an unrealistically high win rate just to break even over time.

Key Takeaway: A stop-loss caps your downside at a predetermined price, set before emotion enters the picture. Risk-reward ratio compares potential loss to potential gain before you even enter a trade — a favorable ratio (like 1:2 or 1:3) means you can be wrong more often than right and still stay profitable over time. Both work together with position sizing to keep any single trade from doing outsized damage. The next lesson covers Transaction Costs: STT, Brokerage & Slippage, including the 2026 STT hike on F&O.

Frequently Asked Questions

What's a "good" risk-reward ratio to aim for?

Many traders aim for at least 1:2, meaning the potential reward is at least twice the risk — though the right ratio depends on your strategy's typical win rate. A higher win-rate strategy can work with a lower ratio, and vice versa.

Should I always use a stop-loss, even for long-term investments?

Stop-losses are most commonly used in active trading with shorter timeframes. Long-term investors often rely more on fundamental conviction and portfolio diversification than a strict price-based stop-loss, though some still use wider stops to guard against a fundamental thesis breaking down.

Can a stop-loss fail to execute at my exact set price?

Yes — in fast-moving or illiquid markets, a stop-loss order can execute at a worse price than set, a form of slippage. This is more common during sharp gaps or high volatility, which is worth factoring in when setting stops on less liquid instruments.

Does a trailing stop-loss guarantee I lock in profit?

It significantly improves the odds of locking in gains as a trade moves favorably, but it's still a market order once triggered — meaning it's subject to the same slippage risk as any other stop-loss in fast-moving conditions.

How does risk-reward ratio relate to position sizing?

They work together but answer different questions — position sizing determines how many shares to buy based on your risk budget, while risk-reward ratio determines whether the trade is worth taking in the first place, regardless of size.