Calcul Position Trading

Position trading is a strategy where traders determine the optimal size of their trades based on risk tolerance, account size, and market conditions. Proper position sizing helps manage risk and maximize potential returns. This guide explains how to calculate position sizes for different trading instruments.

What is Position Trading?

Position trading refers to the practice of determining the appropriate size of a trading position based on risk management principles. Unlike day trading, which involves opening and closing positions within the same day, position traders hold positions for longer periods, often days or weeks.

The key principle in position trading is risk management. Traders calculate how much capital to risk on each trade to ensure that a single losing trade doesn't wipe out their entire account. Common position sizing methods include the 1%, 2%, and 3% of account rules.

Position trading is often used in futures, options, and forex markets where positions can be held overnight. It's particularly important in these markets because leverage amplifies both gains and losses.

How to Calculate Position Size

Calculating position size involves several steps:

Determine your account size
Decide on your risk tolerance (typically 1-3% of account)
Calculate the maximum loss per trade
Determine the stop-loss distance
Calculate the position size based on these factors

The most common formula for position sizing is:

Position Size = (Account Size × Risk Percentage) / (Stop-Loss Distance × Tick Value)

For example, if you have a $10,000 account, want to risk 2% per trade, and your stop-loss is 50 points with a tick value of $10, your position size would be:

Position Size = ($10,000 × 0.02) / (50 × $10) = $200 / $500 = 0.4 shares

Position Sizing Formulas

There are several formulas used for position sizing depending on the trading instrument:

Stocks and ETFs

Position Size (Shares) = (Account Size × Risk Percentage) / (Stop-Loss Distance × Share Price)

Options

Position Size (Contracts) = (Account Size × Risk Percentage) / (Stop-Loss Distance × Contract Multiplier)

Futures

Position Size (Contracts) = (Account Size × Risk Percentage) / (Stop-Loss Distance × Tick Value × Contract Size)

Forex

Position Size (Units) = (Account Size × Risk Percentage) / (Stop-Loss Distance × Pip Value × Leverage)

These formulas help traders determine how many shares, contracts, or units to buy or sell based on their risk tolerance and market conditions.

Example Calculations

Stock Example

You have a $20,000 account and want to risk 1% per trade. You're considering buying shares of Company X at $50 per share with a stop-loss 10 points below the entry price.

Position Size = ($20,000 × 0.01) / (10 × $50) = $200 / $500 = 0.4 shares

You would buy 0.4 shares of Company X, which is 20% of a full share. This means your maximum loss on this trade would be $200 (1% of your account).

Options Example

You have a $15,000 account and want to risk 2% per trade. You're considering buying 100 shares of a call option with a $100 contract multiplier and a stop-loss of $5 per share.

Position Size = ($15,000 × 0.02) / ($5 × $100) = $300 / $500 = 0.6 contracts

You would buy 60 shares of the call option (0.6 contracts), which means your maximum loss on this trade would be $300 (2% of your account).

FAQ

What is the best position sizing rule?: The best position sizing rule depends on your trading style and risk tolerance. Common rules include 1%, 2%, and 3% of account size per trade. Beginners often start with 1% to minimize risk.
How does position sizing affect my trading?: Proper position sizing helps control risk by limiting the amount of capital you can lose on any single trade. It also helps ensure you have enough capital to take advantage of profitable trades.
Can I adjust my position size during a trade?: Yes, you can adjust your position size during a trade if market conditions change. However, be cautious as this can increase risk if not managed properly.
What's the difference between position trading and day trading?: Position trading involves holding positions for longer periods (days or weeks), while day trading involves opening and closing positions within the same day. Position trading typically uses larger position sizes.
How often should I review my position sizing?: You should review your position sizing regularly, especially after significant market moves or changes in your account size. Adjust your position sizes as needed to maintain your risk management strategy.