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Vega: Sensitivity to Volatility

advanced7 min read

Why an option can lose money even when you called the direction right.

VegaHow much an option’s price changes when volatility changes. measures how much an optionThe right, not the obligation, to buy or sell at a set price.’s premium changes when *implied volatilityThe size of price swings — not their direction.* (the market’s expectation of futureA binding agreement to buy or sell at a set price on a future date. movement) changes by 1%. A vegaHow much an option’s price changes when volatility changes. of 8 means the premium rises ~₹8 if implied volatilityThe size of price swings — not their direction. rises 1% — and falls ~₹8 if it drops 1%. Both callsThe right to buy the underlying at a set price — a bullish bet. and putsThe right to sell the underlying at a set price — a bearish bet. gain value when volatility rises.

VegaHow much an option’s price changes when volatility changes. is the answer to the most painful optionsThe right, not the obligation, to buy or sell at a set price. mystery: “I was right about the direction and STILL lost money.” The culprit is almost always a volatilityThe size of price swings — not their direction. crush. Higher expected movement makes an optionThe right, not the obligation, to buy or sell at a set price. more valuable (more chance of a big payoff), so premiums inflate when volatilityThe size of price swings — not their direction. is high — for example, right before earnings. When the event passes, implied volatility collapses, and vegaHow much an option’s price changes when volatility changes. drags the premium down hard — often wiping out the gain from a correct directional callThe right to buy the underlying at a set price — a bullish bet.. You bought expensive (inflated volatility) and the air came out of the price. Vega teaches that what you predict isn’t enough; you must also ask whether volatility is cheap or expensive when you trade.
ExampleBefore earnings, a stock’s ATMWhere an option’s strike sits relative to the current price. callThe right, not the obligation, to buy or sell at a set price. costs ₹120 on sky-high implied volatilityThe size of price swings — not their direction.. Earnings come, the stock rises 3% (you were right!) — but implied volatilityThe size of price swings — not their direction. crashes from 60% to 30%, and vegaHow much an option’s price changes when volatility changes. drags the premium down to ₹90. Correct direction, losing trade, purely because you overpaid for volatility that then evaporated.
Common mistakeBuying optionsThe right, not the obligation, to buy or sell at a set price. right before earnings to “profit from the move,” ignoring that implied volatilityThe size of price swings — not their direction. (and premiums) is already inflated. The post-event volatilityThe size of price swings — not their direction. crush often eats the directional gain — this is why naive earnings-buying so frequently loses. Check whether volatility is cheap or expensive first.
Key takeawayVegaHow much an option’s price changes when volatility changes. = sensitivity to changes in implied volatilityThe size of price swings — not their direction. (rising volatilityThe size of price swings — not their direction. inflates premiums, falling deflates them). It explains losing despite a correct direction: a volatility crush (e.g. post-earnings) drags premiums down via vegaHow much an option’s price changes when volatility changes.. Always ask if volatility is cheap or expensive before buying.
FAQs
How do I avoid getting hurt by a volatility crush?

Don’t buy options when implied volatility is unusually *high* (e.g. right before earnings) unless you account for the crush — consider strategies that are short vega or volatility-neutral instead. The IV Rank/Percentile tools (next module) tell you whether volatility is cheap or expensive *right now*, which decides whether buying or selling premium makes sense.

Related glossary terms
VegaOption GreeksImplied Volatility (IV)Theta (Time Decay)