I got a PM asking why options expiration can cause strange trading.Quote from nitro:
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3) Options expiration is causing strange patterns. That said, the last 1 1/2 hours may be ugly.
nitro
Ok, suppose equity option Market Makers, for whatever reason, are net short coming into today. For example, they could be short calls and long puts.
As the market falls, they are picking up short deltas because most option traders like to be long gamma (not true always, especially options ex week, but on the last day their gamma position is very likely to go back to being long gamma).
What is happening is that they are buying sell-offs because if you are long gamma, whatever your delta position is gets exaggerated by being long gamma as the market goes in your net position direction. Since they are net short, they buy back some of the extra deltas that their gamma generated by buying stock, staying as balanced as possible and locking in profits wherever possible.
I know it is a bit confusing if you are not used to it. The point is that as the day progresses and gets closer to EOD, MMs are less likely to do this kind of hedging because they eliminated all this ex day risk, etc.
Doesn't mean you can predict the market based on this, but it often explains "strange" trading patterns. You might say, fine who cares what they are doing? Remember, one of the biggest if not THE biggest volume clients of the NYSE etc are CBOE option MMs.
nitro