While I don't know, I would assume that the index is market cap weighted, so I don't think that Ariad is going to dominate.
And the index tracks the performance of its components -- Ariad wouldn't rise because a non-public terminal model portfolio rose.
So on those elements, we can agree to disagree. Although earnings is in the offing for Ariad, they pre-announced, so I don't see those results being much of a catalyst. IMO, buying pressure at this time of low news flow is much more likely to arise from external forces.
On your chart, I agree -- I misread the number of periods as days, so yes, it's the same two-day period. That said, I don't think that looking at two stocks that may or may not be part of the index contradicts the underlying idea.
Anyway, we're up and if that's because some shorts got an unwelcome call from their brokers, that a plus.