You'd have to think those selling realise TPD's share price is now anchored to STX's and aren't interested in becoming part of STX. Why sit in TPD when you can take the cash and re-invest it somewhere else? Whereas though buying are doing so to exploit the arbitrage opportunity but also because they are quite happy to become part of STX. As such, by the time December rolls around, the TPD register will have even more pro-STX holders. And at some point this becomes a self-fulfilling prophecy, right? i.e. those who don't want STX stock are more likely to sell in the next couple of months. Will be very surprised if the deal doesn't get through.