What Is Vega in Options?
Vega measures the sensitivity of an option's price to a 1% change in implied volatility (IV). Unlike the other Greeks named after actual Greek letters, Vega is not a Greek letter but is still grouped with them as a core risk metric. If an option has a Vega of 0.15, its price will increase by $0.15 per share ($15 per contract) for every 1% increase in implied volatility, and decrease by the same amount for a 1% decline.
Vega is critically important for understanding how options behave around events that change implied volatility, such as earnings announcements, FDA approvals, economic reports, and geopolitical events. Before these events, implied volatility typically rises as the market anticipates a large move. After the event, IV typically collapses (IV crush), dramatically affecting option prices regardless of what the underlying stock actually does.
Both long calls and long puts have positive Vega, meaning they benefit from rising implied volatility. Short calls and short puts have negative Vega, meaning they benefit from falling IV. This is why selling options before earnings (to capture IV crush) is a popular strategy.
Vega Formula
Vega Calculation Example
- 1T = 7/365 = 0.0192 years, sqrt(T) = 0.1385
- 2d1 = [ln(100/100) + (0.05 + 0.18) × 0.0192] / (0.60 × 0.1385) = 0.00441 / 0.08309 = 0.0531
- 3N'(0.0531) = 0.3984
- 4Vega = 100 × 0.3984 × 0.1385 / 100 = 0.0552 per share
- 5IV crush of 30 points (60% to 30%): 30 × 0.0552 = $1.656 loss per share
- 6Option price at 60% IV: approximately $3.40
- 7Option price after IV crush to 30%: approximately $1.74
- 8Loss from IV crush alone: $1.66 per share, or $166 per contract
Vega by Moneyness and Time to Expiration
| Strike | 7 DTE Vega | 30 DTE Vega | 90 DTE Vega | 180 DTE Vega |
|---|---|---|---|---|
| $90 (Deep ITM) | $0.01 | $0.05 | $0.11 | $0.17 |
| $95 (ITM) | $0.03 | $0.09 | $0.16 | $0.22 |
| $100 (ATM) | $0.06 | $0.12 | $0.20 | $0.28 |
| $105 (OTM) | $0.03 | $0.09 | $0.16 | $0.22 |
| $110 (Deep OTM) | $0.01 | $0.05 | $0.11 | $0.17 |
Understanding IV Crush
IV crush occurs when implied volatility drops sharply, typically after a binary event like an earnings announcement. Before earnings, option prices are inflated because the market expects a large move. Once the uncertainty is resolved (regardless of the direction), IV collapses back to normal levels. For a stock with typical IV of 30%, pre-earnings IV might spike to 50-80%, and then drop back to 30-35% immediately after the announcement.
The financial impact of IV crush is directly proportional to your position's Vega exposure. A position with total Vega of $50 will lose $50 for every 1% drop in IV. If IV drops 20 points after earnings, the position loses $1,000 from IV crush alone, before considering any directional movement. This is why many experienced traders sell options (short Vega) before earnings to profit from IV crush rather than buying options.
Managing Vega Risk
IV Rank measures where current IV sits relative to its 52-week high and low (formula: (current IV - 52w low) / (52w high - 52w low)). IV Percentile measures the percentage of days in the past year with IV below the current level. Both help determine if IV is historically high or low, which guides Vega-based strategies.
Buying at-the-money options before earnings is often a losing strategy despite the expected large move. The stock needs to move MORE than the market-implied expected move to overcome IV crush. Studies show that option buyers before earnings lose money approximately 60-65% of the time.