This is a very good question. And I'd expect more often to see the price go up. But not always.
In this particular example, maybe it can be explained by the fact that there's
more competition or urgency on the sell side rather than the buy side.
Look at this data. This is data from the end of March - from where collective accumulation of investment banks pivoted.
Here are the top buyers and sellers.
As you can see, Morgan Stanley Securities accumulated $25M of shares while on the sell side we see J.P. Morgan with -$14.4M and UBS with -$10M. Basically, in simple terms, UBS and J.P. Morgan were competing to sell to Morgan Stanley Securities.
It's of course more complicated because these brokers represent many clients, but in this market cap space there potentially can be one major fund behind each of these brokers during this period of time.
It's just my guess. I was actually doing this kind of research recently on other stocks within the $500M - $5B market cap space and it's quite a consistent observation. If you take, for example, a period of 3-6 months and identify who accounts for 80% of volume on the sell side and buy side - if on the sell side there are more brokers in this 80% than on the buy side, it often suggests more competition and the price going down.
(20min delay)