Well... Since I'm nowhere as good in research as some of the other guys on here, I may have found some answers that you guys can further investigate.
It seems like Credit Suisse has done something similar over at LYC, they:
Initially borrowed (5.56%) 226m shares on 4 Aug 2017 (close was $1.40)
They then dumped 38m or so shares on 7-8 Aug (close was $1.50 and $1.55 respectively)
They ceased to be substantial holder
They borrowed (6.69%) 37m shares on 5 Jan 2018 (close was $2.33)
They dumped 7m shares from 8-10 Jan (causing share price to drop from $2.33 to $2.24)
They dumped more from 11-12 Jan, ceasing to be substantial holder (not sure how long they kept dumping for, but on 9 Feb, they reached a low of $1.82)
LYC has since gone up to a $2.96 high in May - 3 months after their low.
It doesn't seem like CS' dumping really affected the share price toooo much, but it seems like this isn't their first time doing something like this. Borrowing shares and dumping.
Hope someone can take what I found and figure out why.