what is going on ?

This stock has traded in a tight range over the last few days however what has been noticeable is the larger than normal sized orders. What is even more perplexing is that these orders are being accomodated quite easily. Given that the 20th largest shareholder owns only approx 400,000 shares the way I see it only one of three things can be happening

1 - Large shareholders are bailing out - doubt it
2 - Instos buying - but from who ?
3.- Short selling - ( not permissable on this stock )

Any thoughts ? My guess is that there is news on the horizon. Doubt that mediation will settle the legal matter. The company in its most recent ann. states that GSK will not have likely finished their discovery of documents by 9 Sept so I doubt we'll hear much on this topic. Has me baffled