Fixed-Percentage Risk
Learn fixed-percentage risk sizing, risk units, compounding effects, drawdown behaviour and why the percentage should apply to loss-at-stop rather than position notional.
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Fixed-percentage risk sizing limits the planned loss on each trade to a fixed fraction of current account equity, so position size automatically contracts after losses and expands after gains.
Learning objectives
- Calculate a monetary risk budget from current equity and a chosen percentage.
- Convert that risk budget into position size using the actual stop distance.
- Explain how fixed-percentage sizing affects compounding, drawdowns and recovery.
What it is
Under fixed-percentage risk, a trader chooses a fraction of current equity—such as 0.5% or 1%—as the maximum planned loss if a trade reaches its predefined stop. With £50,000 of equity and a 1% rule, the risk budget is £500.
The percentage applies to the loss at the invalidation point, not to the cash value of the position. A £20,000 position can risk only £500 if its effective stop is 2.5%; a £5,000 position can risk more than £500 if it is leveraged and the stop is wide.
Because the rule is based on current equity, position risk contracts after losses. This creates a negative-feedback mechanism that slows absolute losses during a drawdown.
How it works
The basic sequence is equity → risk percentage → monetary risk → stop distance → units. Reversing that order—deciding how many coins to buy first and then inventing a stop—breaks the risk process.
At 1% risk per trade, ten consecutive full-risk losses do not reduce equity by exactly 10% because each later 1% is calculated from a smaller base. Starting at £100,000, ten sequential 1% losses leave about £90,438, a drawdown of roughly 9.56%.
Recovery math is asymmetric. A 20% loss requires a 25% gain to return to the starting value; a 50% loss requires a 100% gain. The purpose of small risk units is therefore not merely emotional comfort—it protects the compounding base.
Portfolio context still matters. Five simultaneous trades each risking 1% can create close to 5% aggregate loss if they are driven by the same market factor. A per-trade limit should sit inside a portfolio risk cap.
How to analyse and apply it
| Check | Why it matters | What to verify |
|---|---|---|
| Risk percentage | Sets planned loss per trade. | Choose a level consistent with strategy drawdown and portfolio correlation. |
| Current equity | Makes risk scale with the account. | Use marked-to-market equity, not the original deposit. |
| Stop loss per unit | Converts risk budget into units. | Include contract multiplier and quote/collateral currency. |
| Aggregate open risk | Prevents many small trades becoming one large bet. | Sum or stress correlated positions at their stops. |
Risk rules should be written before a live position is opened and evaluated across many trades or scenarios. A control that is changed only after losses appear is discretionary damage control, not a repeatable risk system.
Worked example and thought exercise
A £60,000 account uses a 0.75% risk rule. The monetary risk budget is £450. BTC is £50,000 and the trade’s invalidation is 3% below entry, or £1,500 per BTC. Position size is £450 ÷ £1,500 = 0.30 BTC, equivalent to £15,000 notional.
If the trader instead buys 1 BTC because £50,000 feels like a reasonable position, the same 3% stop risks £1,500, or 2.5% of account equity—more than three times the intended risk.
Thought exercise: if three highly correlated altcoin trades each risk 0.75%, what portfolio loss could occur if a market-wide shock hits all three stops together?
Common mistakes and practical workflow
- Applying the percentage to position notional instead of loss at the stop.
- Using starting equity rather than current marked-to-market equity.
- Treating every open trade as independent when their drivers are highly correlated.
- Assuming the stop guarantees the planned loss during gaps or illiquid execution.
Practical workflow
- Mark current account equity.
- Set the per-trade risk percentage and portfolio open-risk ceiling.
- Define invalidation and calculate loss per unit including contract mechanics.
- Calculate units from the risk budget; round down if exchange increments require it.
- Stress slippage and correlation before submitting the order.
✅ Knowledge checkpoint
- What does a 1% fixed-risk rule actually limit?
- Why does risk in pounds fall after a drawdown under this method?
- How do you convert a £500 risk budget and £2,000-per-unit stop loss into units?
- Why can five 1% trades create more than 1% portfolio risk?
FAQs
❓ Is 1% the correct risk percentage for everyone?
No. It is a convention, not a universal optimum. Appropriate risk depends on strategy volatility, expected losing streaks, leverage, liquidity and portfolio correlation.
❓ Should the percentage be based on balance or equity?
For live risk control, marked-to-market equity is generally the more conservative base because it incorporates unrealised gains and losses.
❓ Does a stop guarantee the percentage loss?
No. Slippage, gaps, liquidation mechanics and market outages can cause a larger realised loss.
❓ Why use a percentage instead of a fixed pound amount?
A percentage automatically scales down after losses and up after gains, keeping risk proportional to the account.
📋 Summary
Fixed-percentage risk turns each trade into a controlled fraction of current equity. Its strength comes from coupling a monetary risk budget to a real invalidation point, while portfolio caps and slippage stresses prevent individually small trades from combining into an unexpectedly large drawdown.
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