It would appear that some one is buying ETP in big chunks. We saw that during the day - twice, a 50k share block buy at 10:00 AM, pps of 52.09 and then again at 11:47 another 50k share block, pps of 52.17. Seems total volume during normal trading was about 800k shares, quite light compared to the 3-month daily average of 1.4 million.
Then, the interesting trade in AH showed up - 385,000 shares traded at 4:27 PM, pps of 51.84 - matching the eod trading.
That 385k trade represented almost 50% of the normal trading today, thus it seems that the buyer made this a pre-arranged deal to be recorded in the AH trading so as to not causing a big uptick in the pps.