Just to name a few stocks, these had very large volume in after hours 6/26 (way above normal shares traded)
Spy 14.71 million
Qqq 6.18 million
Microsoft 54.39 million
Google 21.99 million (this was the strangest, there was 31.7 million shares sold at 4pm alone versus 60.36 million for the entire day session)
Is this due to quarterly rebalancing?