How high is high and how low is low.

Buying when the VIX is high and selling when it is low have proved profitable in recent years. However, so has buying during market spills and selling during market peaks.

The real question is how high is high and how low is low.

For instance, an investor may have been tempted to buy into the market on Friday, October 16, 1987, when the VIX reached 40. Yet such a purchase would have proved disastrous given the record 1-day collapse that followed on Monday.