It looks like an attempt to sell just to make Bitcoin prices lower.
I wonder why they did not just do that. At one point it cost only around 200 BTC to break 115.
Selling in one wave doens't do that much damage and they had to keep an extra if the price bounced back.... like it happend.......
Also they need to restock on their way down ....for further dumps
But this pure speculation, and I really doubt that it was an attack.