Vega vs Vol Crush

The rate of change of an option's price relative to a 1% change in implied volatility; long options have positive vega (gain value when IV rises); short options have negative vega (lose value when IV rises); the primary risk in bought options around anticipated events.

The rapid compression of implied volatility that frequently occurs immediately after a highly anticipated event resolves; causes bought options to lose vega value even when the price move was favorable; the primary reason option buyers around events often lose money despite being correct on direction.