It's funny. I'm not sure who it was but someone predicted that, while we were in the $15.00 range, they would not start the buyback until we hit $22+.
CVRR has a variable dividend which makes it impossible to predict. They just simply use the last quarter's dividend and multiply by 4. It's probably completely automated too.
Could be someone trying to create panic for the early morning trading to cover their short. I doubt that anyone would be stupid enough to sell a couple 100k shares in one order at market.
I don't know the exact percentage. But if you look at the securities sales log the spike in the number of short sales is quite obvious.