High Vol Rise on Op-ex Day – Good or Bad?

Option expiration on Friday saw the market rise on exceptionally high volume. Over the last 13 years high volume rises on an up op-ex day have often led to a selloff.

Could it be different this time? If it opens here then it already is. In no instance over the last 11 years did the market gap higher by as much as 0.5%. It did manage to do so on 12/21/98 – exactly 11 years ago. It also added to the gains and closed above the open that day. Overall implications appear short-term bearish though.