Having learnt from experience myself, it can be a wild ride when sentiment swings.
Its unfortunately a double-pronged attack in many cases when the insto's change their mind.
Firstly, they start to sell down their holdings which can depress the price (especially if there are no other large players wanting to pick up the stock). Then, the lack of accumulation by big guys mean even if good news does come out, there just isn't the buying momentum or volume to push prices back up.
Good luck to holders, I'm sure in the long term CLH will still be around and making money, just a hard one to pick what its share price will settle at in the mean time.
CLH Price at posting:
95.0¢ Sentiment: None Disclosure: Not Held