Mistake 1, critical severity
Ignoring Theta (Time Decay)
Buying options without understanding that they lose value every day. Many traders hold long options too long, watching time decay erode their position even when direction is right.
The fix
Know your theta before entering. If your option loses $20/day in theta, the stock needs to move enough to overcome that decay. Use 45-60 DTE for swing trades to reduce daily theta impact.
What it looks like. Buy AAPL $190 call at $5.00. Theta is -$0.15/day. After 15 days, AAPL is unchanged. Option worth $2.75. Lost $2.25 (45%) to time decay alone. Direction was neutral but the position lost significantly.
Mistake 2, critical severity
Ignoring Vega (Volatility Sensitivity)
Buying options when IV is high without considering that IV can drop, crushing the option value. Being right on direction but wrong on volatility still loses money.
The fix
Check IV rank before buying. If above 50%, use spreads to reduce vega. Understand your vega exposure: option vega x number of contracts = dollar change per 1% IV move.
What it looks like. Buy straddle on NVDA before earnings. Vega is $1.50 per contract. IV drops 20 points after earnings. Vega loss: $30 per contract ($3,000 on 10 contracts). Stock moves 3% but you still lose.
Mistake 3, high severity
Ignoring Delta (Directional Exposure)
Not understanding how much your position moves with the stock. Buying 10 ATM calls has the same delta as owning 500 shares. Many traders do not realize their effective position size.
The fix
Calculate total position delta before trading: delta x 100 x contracts. Use this to understand your effective stock exposure. Manage total portfolio delta to avoid concentration.
What it looks like. Buy 10 TSLA ATM calls (delta 0.50). Total delta: 500. That is equivalent to owning 500 shares ($125,000 in TSLA exposure). TSLA drops 5%: position loses $6,250. Most traders do not realize they had this much exposure.
Mistake 4, high severity
Ignoring Gamma (Rate of Delta Change)
Not understanding that near-expiration options have extreme gamma. Small stock moves create large position changes. 0DTE options can double or zero in minutes.
The fix
Reduce position sizes significantly for short-dated options. Gamma increases exponentially in the last week. Set strict stop-losses on positions with high gamma. Avoid ATM options in the final 3 days.
What it looks like. Sell ATM iron condor with 2 DTE. Stock moves 1.5%. Gamma accelerates delta. Position that was flat at open becomes $500 negative by noon. Short-dated options move much faster than expected.
Mistake 5, medium severity
Ignoring Combined Greek Exposure
Monitoring Greeks of individual positions but not the portfolio total. Five bullish positions all have positive delta and negative theta. The portfolio is heavily directional even if each trade seems reasonable.
The fix
Track portfolio-level Greeks daily. Sum all delta, theta, vega, and gamma across positions. Set limits: total delta under 500, total theta should fund risk budget. Use ApexVol's Greeks exposure tool.
What it looks like. Five bull call spreads on different stocks. Each has +50 delta. Portfolio total: +250 delta (equivalent to 250 shares of SPY). Market drops 2%. All positions lose simultaneously. Portfolio-level risk was 5x what each individual position suggested.
