How Does Vega Measure an Option’s Sensitivity to Market Sentiment?

Vega measures the change in an option's price for every 1% change in Implied Volatility (IV). Since IV is largely a reflection of market participants' expectations and fear (sentiment) regarding future price swings, Vega directly quantifies how much an option's price will change due to a shift in market sentiment.

High Vega means the option is highly sensitive to sentiment changes.