I thought there is Pinning effect on option expiration day, but it was not obvious on Google on Feb. 20 (last Friday). On Friday afternoon, I thought GOOG was going to pin down to $340, but it actually started to drift to $350, reaching $349 at some time in the afternoon, and then finally settled down at $347. Where is the Pinning effect? The Pinning effect was not obvious on many other stocks too. What happened? Any thoughts?