That was fast
A day after "fear" rose enough to push the VIX above 40, it fell back below. This shows that traders are only flirting with the potential for a sustained rout - most major declines see volatility spike and then stay high until the panic subsides. It's not foolproof, as it preceded big losses in September 2008 and March of this year. But 3 months later, only 1 out of 25 signals showed a loss greater than -3% in the S&P 500.