Quote from yip1997:
I expect IV is larger than HV in normal market environment. Recently I found that IV is lower than HV. Under what conditions does it happen? How does it affect our trading strategies?
The condition we just had starting just before May expiration: Rapid IV expansion followed by contraction. It takes HV a while to catch up (or down).
Generally, it's a time of caution for spread traders as the market may not be fully settled into its new "routine". You're going to get less premium for the same time and distance. This isn't reassuring after the market has been a little nutty during its high IV period.
However I'm totally spoiled to anything else now...it is unfreakingbelievable...