Below: Five quarters of massive trades in one interactive chart.
Sell-offs dominated the hedge fund news last last year, especially the big dump by State Street in the September 2016 quarter. The first of two big buys by Warren Buffett's Berkshire Hathaway was the headline in February. The big blip in the March quarter (reported in May) was created by consolidation of several Blackrock Funds. The June quarter, by comparison, was so quiet that what shows up as the biggest buy was actually created by the merger of the Janus Fund and the Henderson Group, both major holders of Apple.
UPDATE: Friend-of-the-blog Ken Cheng complained that the changing scales and automatic re-sorting make it hard to read the chart above. This one's for you, Ken: