Risk management: risk per trade, the position formula and drawdown control

Rule one: cap risk per trade

Risk per trade is the maximum reduction in account equity on a single trade once entry and stop have both been executed. The common practice is to keep it between 0.5% and 2% of account equity. That range is not mysticism; it directly determines how many consecutive losses you can survive:

• 1% risk per trade: ten consecutive losses reduce equity by about 9.6%
• 2% risk per trade: ten consecutive losses reduce equity by about 18.3%
• 5% risk per trade: ten consecutive losses reduce equity by about 40.1%

With the same number of losses, a different cap produces outcomes that differ by more than four times. That is why the risk cap deserves to be settled before the entry signal.

Rule two: derive position size from the stop distance

Position size is not chosen first; it is derived. The formula:

• Amount at risk = account equity x risk cap per trade
• Value per pip per standard lot = as calculated in Lesson 02
• Lots = amount at risk / (stop distance in pips x value per pip per standard lot)

With 10,000 dollars of equity, a 1% risk cap, a EUR/USD trade and a 50-pip stop: lots = 100 / (50 x 10) = 0.2 standard lots. If the stop distance widens to 100 pips, the size halves to 0.1 standard lots and the amount at risk is unchanged.

The value of this formula is that it binds the stop distance to the position size. The wider the stop, the smaller the size, so risk per trade stays constant.

Rule three: control total exposure

Beyond risk per trade, total simultaneous risk also needs a limit. When several positions depend on the same driver — being short EUR/USD and short GBP/USD at once is in substance one long dollar position — they should be treated as one risk. The correlation discussion in Lesson 07 directly determines the ceiling on total exposure here.

Rule four: the asymmetry of drawdown

Drawdown and recovery are not symmetrical: a 10% loss needs an 11.1% gain to recover; a 20% loss needs 25%; a 50% loss needs 100%; an 80% loss needs 400%. The goal of risk management is therefore not to maximise the return on any single trade but to avoid a drawdown that cannot be recovered from.

That supports setting a stop line: when the account drawdown reaches a chosen percentage, say 10%, pause trading and reassess. The point of the stop line is that it turns "keep losing" into an active decision rather than a default state.

Rule five: never increase size to win losses back

Raising size after a losing run pushes risk per trade beyond the original cap and moves the drawdown faster towards the unrecoverable zone. Academic work offers a related perspective: in a 2000 study published in the Journal of Finance, Barber and Odean analysed tens of thousands of individual investor accounts and found that the most active fifth of investors earned an average net return of about 11.4% a year against a market return of about 17.9% over the same period. The more frequently they traded, the lower the net return, because of trading costs and deteriorating decision quality.

That conclusion cannot be extrapolated directly to margin forex trading, but the directional message is clear: frequent trading and larger size are usually not the path to better returns.

The five rules on one page

• Risk per trade: 0.5%–2% of equity, fixed in advance and not adjusted with emotion
• Position size: derived from risk amount / (stop distance x value per pip), never chosen first
• Total exposure: highly correlated positions are combined when calculating risk
• Stop line: pause trading when the drawdown reaches a preset percentage
• Losing streaks: cut size first, then judge whether the strategy has broken (Lesson 09)

Lesson summary and self-check

• The cap on risk per trade determines how many consecutive losses you can survive, and matters more than the entry signal.
• Position size is derived from the stop distance; a wider stop means a smaller size and an unchanged amount at risk.
• Drawdown is asymmetric: a 50% loss needs a 100% gain to recover.
• Overtrading and larger size usually damage net returns.

Self-check: (1) With 20,000 dollars of equity, a 1% risk cap and an 80-pip stop, how many lots of USD/JPY (about 6.32 dollars per pip per standard lot) should you trade? (2) Why does averaging down conflict with the rules in this lesson?