Stocks are rallying so fast it's creating a volatility dynamic that's only been seen four times in history — and equity prices kept climbing following each instance. Implied volatility in the S&P 500 and Nasdaq-100 has held firm despite record after record, with the VIX little changed since slipping below 18 in mid-April despite the S&P 500 up 7% since. It's a byproduct of both aggressive call-buying in high-flying stocks and broad-market hedging by traders who see the VIX as a relative value