If the spot VIX is the implied vol off of the options on the SPX Index. But which tradable product would that be? Can’t you technically only buy ETF’s that track the SPX (SPY) or buy the ES futures. The spot VIX index is calculated off the S&P500 futures or the ETF’s?
Second, if the spot is based on the Cash SPX. What would the implied vol for options on 3Month S&P futures be? Would it be the same as the 3 Month VIX futures contracts? What is the relationship between the implied vol on the SPX futures contracts and the equivalent time period VIX futures. wouldn't they be exactly the same?