Lol I have no idea who is selling let alone why. If I had to guess I'd say it's mostly finance managers panicking and selling the only thing they can sell during a weekend In fears that there will be deflation. 

What's so funny is that if there is indeed deflation and a sudden and dramatic strengthening of the dollar, the dollar handlers will intervene SO fast and SO hard the deflation won't last more than a few weeks and everything will moon by next year just in time for the bitcoin cycle.