Vega
How sensitive your option is to volatility
What is Vega?
Vega is like surge pricing. When the market is uncertain (high IV), options cost more. When uncertainty disappears, prices drop — even if nothing else changed. Vega measures how much that surge pricing affects you.
Vega measures how much your option's price changes when implied volatility (IV) moves by 1 percentage point. If your option has vega of 0.25 and IV rises from 20% to 21%, your option gains approximately $0.25 per share ($25 per contract). If IV falls 1%, you lose $0.25.
Implied volatility is the market's consensus forecast for how much the stock will move. When uncertainty spikes — ahead of earnings, major economic reports, or market events — IV rises and options get more expensive. When uncertainty resolves, IV collapses and options get cheaper. Vega tells you exactly how much your position is affected by those IV swings.
You can be right about direction and still lose money if IV collapses after you buy. This is called an "IV crush" — and it happens to nearly everyone who buys options the day before earnings for the first time. Vega is why.
| IV Rank / Percentile | What It Means | Option Buying | Option Selling |
|---|---|---|---|
| 0–20 (Low IV) | Options cheap vs history | Favorable — low vega cost | Unfavorable — low premium collected |
| 20–50 (Normal IV) | Options fairly priced | Neutral | Neutral |
| 50–80 (Elevated IV) | Options expensive vs history | Caution — vega can hurt if IV drops | Favorable — rich premium |
| 80–100 (High IV) | Options very expensive | High risk — IV crush likely | Best time to sell premium |
Vega is highest for ATM options with long time to expiry. A 6-month ATM option has much more vega than a 1-week ATM option — it has more "IV exposure" because IV can change a lot over 6 months. Near expiry, vega shrinks because there's little time left for IV changes to matter. This is why LEAPS traders are far more sensitive to IV movements than weekly option traders.
Option Price vs Implied Volatility
How to Read This Chart
- X-axis = implied volatility level (low to high).
- Y-axis = option price. Higher IV → more expensive options.
- The slope at any point is vega — a steeper slope means the option is more sensitive to IV changes.
- IV crush: imagine the stock moving from right to left on this chart after earnings. Even if you gained on delta, vega destroyed value as IV collapsed.
Frequently Asked
What exactly is "IV crush" and why does it matter?
Before earnings, IV rises because nobody knows how much the stock will move. After earnings, that uncertainty disappears and IV collapses — sometimes by 30–60% in a single day. If you bought options the day before earnings, your vega exposure means this IV collapse destroys significant option value even if the stock moved in your favor. The stock might be up 3%, but your call might be down 20%. That's IV crush.
Do calls and puts have the same vega?
Yes — for the same strike, expiry, and underlying, calls and puts have identical vega. Both increase in value when IV rises, and both lose value when IV falls. Vega doesn't care about direction — it only measures sensitivity to uncertainty. This symmetry is what makes volatility trading possible (buying straddles to profit from IV expansion regardless of direction).
How do I know if IV is currently high or low?
Raw IV alone means little without context. SPY at 20% IV might be high or low depending on history. Use IV Rank (IVR): where does current IV sit within the past year's range? IVR of 80% means IV is in the top 20% of its historical range — options are expensive. IVR below 30% means options are cheap relative to history. Most brokerage platforms show IVR directly.
If IV is high, should I always sell options?
High IV means you collect rich premium when selling — but it also means the market expects a big move. The premium is high for a reason. Selling high-IV options near earnings can be lucrative if the stock doesn't move as much as expected, but a single large move can wipe out many months of premium. Understand why IV is high before deciding to sell.
A Real Example
TSLA reports earnings tomorrow. IV is at 90% (elevated). You buy an ATM call for $18.00. Delta = 0.50, Vega = 0.35.
Delta gain: 0.50 × $20 × 100 = +$1,000. Looks great so far.
Vega loss: 0.35 × 45 × 100 = −$1,575. IV crush wipes out your delta gain and then some.
+$1,000 from delta − $1,575 from vega = −$575 net loss. TSLA went up 8% and you lost money. This happens more often than most beginners expect.
The stock move was real. The loss was real. Vega is why. Before buying options into any expected event, always check whether IV is elevated and estimate how much IV might drop — that number can dominate your P&L completely.
What Beginners Get Wrong
Quick Quiz
Answer all questions and check your score.
1 Vega measures how much an option price changes when:
2 What is "IV crush"?
3 A call has vega 0.25. Implied volatility rises by 3%. The option price changes by approximately:
4 Vega is highest for:
5 Buying options right before earnings is primarily risky because of: