It’s been one of the wildest stock markets on record lately but you wouldn’t have known it looking at the Cboe Volatility Index. Friday’s sell-off just made things a lot clearer.

The non-stop, two-month 80% rally in semiconductor stocks that added roughly half a trillion dollars in market cap to the Nasdaq 100, spurred one of the most successful ETF launches in history, and birthed dozens of eye-popping, parabolic single stock moves, finally hit a wall on Friday as the VanEck Semiconductor ETF (SMH) dropped almost 10% at its low.

The VIX, which had just touched the lowest level since January on Thursday, posted its biggest single-day pop since March. S&P 500 index options trading reached a record 7.8 million contracts at Cboe on Friday,…