How sensitive are equity option prices to changes in prices in their underlyings (large cap stocks)? The reason I'm asking is b/c I was looking at some option quotes on CBOE.com for stocks that moved big time (say 25% or so on a given day) and barely anything changed in option chains! I was under the assumption that if I happened to have a stock that was hedged with puts I'd be more or less limited from the downside risk. And yet the put prices bearly moved as the stocks plummeted. What's going on? Or is this protective put thing only gonna work over longer horizons? Thanks.