Quote from opt789:
This is not really correct. There are two separate and distinct items when referring to the VIX. You can trade VIX futures and the options based on them, but this is not the cash VIX index that everyone quotes. There are, of course, related but they are not the same and should not be traded as such.
The VIX index is 24.17 while the Aug futures contract is 20.17 and the Sep is 19.75. So it is a misnomer to say you can "short the VIX at 24". You have two choices: one is to short the Aug futures at about 20 or use the options to create an appropriate position, and the second is to use the SPX options in order to create a short vega position. You could short the Aug VIX futures and the cash VIX falls 4 points over the next few weeks and you end up not making any money.