Vega, and losing money on a flat day
Vega is the change in an option price for a one point move in implied volatility. The UBER $72.50 call carries $8.41 of vega per contract, so a five point rise in implied volatility costs the seller about $43 even if the stock never moves. It is the only Greek that is purely about opinion.
Delta, gamma and theta all describe reactions to things that happened: the stock moved, a day passed. Vega describes a reaction to the market changing its mind.
The number
Short the October 17 $72.50 call on UBER at 32 percent implied volatility, collected for $153. Vega is $8.41 per contract per volatility point.
| Implied volatility | Option worth | Seller mark to market |
|---|---|---|
| 27% | $112 | +$41 |
| 32% (where you sold) | $153 | $0 |
| 37% | $195 | -$43 |
| 45% | $266 | -$113 |
UBER is $68.40 in every row. No time has passed. The position is down $113 in the last one purely because the market decided the stock is riskier than it thought this morning.
That is the experience vega describes, and it is the one that most confuses people new to selling. You were right about direction, nothing happened, and the screen is red.
Vega grows with time, and it grows fast
| Days to expiry | Vega | Option price |
|---|---|---|
| 7 | $3.78 | $124 |
| 21 | $6.53 | $218 |
| 42 | $9.21 | $312 |
| 90 | $13.41 | $467 |
| 365 | $26.15 | $1,000 |
A one year contract is seven times as exposed to a volatility move as a one week contract. The reason is intuitive: a change in the expected pace of movement compounds over more remaining days.
This is the practical case against selling long-dated premium for the yield. A 365-day option pays more in absolute dollars, decays more slowly per day, and hands you seven times the volatility exposure. You are no longer selling time. You are taking a position on the volatility level, for a year.
Vega is also largest at the money
Same reason gamma and theta are. The at-the-money contract holds the most extrinsic value, and vega acts on extrinsic value. A deep in-the-money call is mostly intrinsic and barely notices a volatility move. A far out-of-the-money one has so little value that a percentage change in it is small in dollars.
Every premium seller is short vega
Structurally, permanently, in every position on this site. Selling an option means selling volatility exposure, and it means the position loses when implied volatility rises.
The uncomfortable part is the correlation. Implied volatility rises when markets fall. So a short-premium book takes a delta loss and a vega loss in the same session, from the same event, and across every position at once because the volatility move is market-wide even when the positions are not.
Vega is the mechanism by which "five uncorrelated positions" turn out to be one.
Using it
- Sell when implied volatility is high for that name, not high in absolute terms. Selling vega at 20 percent and watching it go to 35 is how a good directional call becomes a losing month. The two standard ways of judging that disagree with each other, and both have a calendar trap.
- Shorter dated is less vega. If you have a view on direction and not on volatility, the 30 to 45 day window carries roughly a third of the vega of a one year contract per unit of premium.
- Mark to market is not the trade. A vega loss on a position you intend to hold to expiry is a paper loss that decays away with the contract, provided the stock behaves. Provided.
- Watch earnings. Implied volatility climbs into a print and collapses after it, which is a scheduled vega event you can see coming. Both sides of that trade are worked here.
OptionsKing scores every candidate strike on a deterministic 0 to 100 scale, blends that score with the return on the capital the trade ties up, and shows you the highest-ranked handful. There is no minimum score. How it works covers what the ranking does and does not tell you.
Questions people actually ask
What is vega in options?
The change in an option price for a one percentage point move in implied volatility. The UBER $72.50 call carried $8.41 of vega, so a five point rise cost the seller about $43 with the stock unchanged.
Why did my short option lose money when the stock did not move?
Almost certainly vega. If implied volatility rose, the contract you are short became more expensive to buy back. In the worked example a move from 32 to 45 percent implied volatility cost $113 with the stock flat.
Do longer-dated options have more vega?
Much more. A 365-day at-the-money contract carried $26.15 of vega against $3.78 for a 7-day one, so selling long-dated premium is largely a position on the volatility level rather than on time decay.
Are option sellers short vega?
Always. Selling premium means losing when implied volatility rises, and implied volatility rises when markets fall, so the vega loss and the delta loss arrive together and across every position at once.
Sources
Rules and thresholds above were checked against these documents on August 4, 2026. Exchange and broker rules change. Confirm anything you are about to act on with your own broker.
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Do the math on your own trade
Every price in this article is an illustrative worked example, not a quote. Read The Greeks for the rest of the series, and the disclaimer before you act on any of it. Selling options carries real risk of loss, and the loss can be far larger than the premium you collected.