RISK MANAGEMENT January 27, 2026

Position Sizing: Turning MU's 61% Gain into Maximum Profit

Micron gained 61.8% in 57 days. But your profit depended entirely on position size. Learn Kelly Criterion, ATR-based sizing, and portfolio heat management—the difference between $6,180 and $18,540.

💰 The Position Sizing Impact

Too Small (1%)

$10,000 account
Position: $100
Profit: $61.80

Optimal (15%)

$10,000 account
Position: $1,500
Profit: $927

Too Large (50%)

$10,000 account
Position: $5,000
Risk: Account blow-up

The 3 Position Sizing Methods

Method 1: Fixed Percentage (Beginner)

Risk a fixed percentage of your account on each trade. Simple but effective.

Formula:

Position Size = (Account Size × Risk %) / (Entry - Stop Loss)
Example (MU Trade):
Account: $10,000
Risk: 2% = $200
Entry: $240.46, Stop: $228.44
Risk per share: $12.02
Position: $200 / $12.02 = 16.6 shares = $3,992

Rule: Never risk more than 2% per trade. This allows 50 consecutive losses before account wipeout.

Method 2: ATR-Based Sizing (Intermediate)

Average True Range (ATR) measures volatility. Size positions inversely to volatility—smaller positions for volatile stocks.

ATR Formula:

ATR = Average of True Range over 14 days
True Range = Max of:
• High - Low
• |High - Previous Close|
• |Low - Previous Close|
MU's ATR (Dec 1): $8.50
Position Size = (Account × Risk %) / (ATR × 2)
= ($10,000 × 2%) / ($8.50 × 2) = 11.7 shares

Why ATR Works: Volatile stocks need wider stops = smaller positions. ATR automatically adjusts for this.

Method 3: Kelly Criterion (Advanced)

Mathematically optimal position size based on win rate and average win/loss ratio. Used by professional traders.

Kelly Formula:

Kelly % = W - [(1 - W) / R]
W = Win rate (decimal)
R = Average Win / Average Loss
Your Stats:
Win Rate: 72% = 0.72
Avg Win: $450, Avg Loss: $150
R = $450 / $150 = 3.0
Kelly = 0.72 - [(1 - 0.72) / 3.0] = 0.627 = 62.7%
Half Kelly (safer) = 31.4%

Warning: Full Kelly is aggressive. Use Half Kelly (divide by 2) for real trading. Still aggressive but safer.

Portfolio Heat Management

Portfolio heat = total risk across all open positions. Critical for avoiding catastrophic losses.

Portfolio Heat Rules:

• Max 6% total heat - Never risk more than 6% across all trades
• 2% per trade - Individual position risk limit
• Max 3 positions - 3 trades × 2% = 6% total heat
• Reduce size - If 3 trades open, new trades get 1% risk

Example: You have 2 trades open (4% heat). MU signal triggers. Risk only 2% on MU to stay at 6% total heat.

Scaling In and Out

Scaling In (Building Position)

Start with 50% position. Add 25% if trade moves 5% in your favor. Add final 25% at 10% gain.

MU Entry: $240.46
• Initial: 50% position (8 shares)
• Add at $252 (+5%): 25% more (4 shares)
• Add at $264 (+10%): 25% more (4 shares)
Total: 16 shares, avg cost $248.46

Scaling Out (Taking Profits)

Lock in profits progressively. Never let a big winner turn into a loser.

• Sell 33% at +15% ($276)
• Sell 33% at +30% ($312)
• Trail 34% with 20-day MA
Result: Locked $3,000, caught extended move to $389

The MU Trade: 3 Position Sizes Compared

Method Shares Cost Profit Return
Fixed 2% 16.6 $3,992 $2,467 61.8%
ATR-Based 11.7 $2,813 $1,739 61.8%
Half Kelly 52.1 $12,528 $7,742 61.8%

Same trade, same percentage gain, but 3x profit difference between conservative and aggressive sizing.

Position Sizing Mistakes to Avoid

❌ Mistake 1: Equal Dollar Amounts

Buying $5,000 of every stock ignores volatility and risk. A $5,000 position in a volatile penny stock is much riskier than $5,000 in AAPL.

❌ Mistake 2: Ignoring Portfolio Heat

Taking 5 trades at 2% each = 10% total risk. One bad day wipes out 10% of your account. Limit total heat to 6%.

❌ Mistake 3: Revenge Trading (Oversizing)

After a loss, doubling position size to "make it back" is the fastest way to blow up an account. Stick to your system.

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This analysis is for educational purposes only. Past performance does not guarantee future results.

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