Institutions are not top-slicing.
Any holder of > 3% (only institutions that we know about) would have to declare their new holding, and no such declarations.
And for any funds, the partial profit normally has little significance at fund level, small % of the total.....
In my experience they normally like to let things run......
whereas private investors often chicken out and like to take some profits, to spend on the wife, or on Xmas .....
or to tell their friends or wife how good an investor they are !!
(' I sold some shares and made 500 quid....so I'll get this round, mates'
'Wow, Fred, tell us how you do it')