Gap and Runs

I can't remember the last time we had a big gap up and a move lower in first two hours.  It has almost always been a chase for risk right off the opening and we move higher substantially in the first hour.  And by lunch time, we are pretty much done with the day's upside.  I have a strong feeling that the algos and the quants are all over this pattern and buying hand over fist in the first 30 minutes of the day.  Just an observation on a big gap up day.