The sell off is from a large holder or holders that have been in...

The sell off is from a large holder or holders that have been in early and are sitting on good profits. They sell off before spudding to reduce their risk or even be free carried. That way they have heaps of upside and no downside.
It is now just a matter of how much more stock they need to sell to get to a free carried position. They obviously got in below the current SP.
You cannot blame them it is a prudent form of investing.

Lets hope they reach their goal soon