"They probably shorted upon the bad news" - once and for all,...

"They probably shorted upon the bad news" - once and for all, you can't short what you own. To be short a stock, you have to be 'short of it' as in 'not have enough' as in 'Dave, we need 2 sausages, 3 rashers of bacon and an egg for breakfast, do we have enough?' 'nah sorry Bazza, we're short bacon'. Fidelity still own 23m shares so they aren't short, nor can they short sell until they have zero or less shares. They're just selling, just like all the longs:

of the 89.5m shares sold on market since the Galderma announcement, only 5.1m were short sold - and that's a gross number, many will have been traders who covered same day.

The reason the stock is going down now is because the longs are selling.