It does get kind of irritating all this talk of Bitcoin 2.0 when anyone that's been watching it a while is eager with anticipation for the great 1.0, the only good thing is its a bit like jurnos writing about "Bit Coin" with an air of professionalism

On-topic, there's a lot of views on who's doing the dumping and they all hint at a blind spot in human nature, looking for a single answer when usually there's a multitude of them. If there was a single cause then here is probably the least likely place to find it, this place is full of agenda driven posters and anyone with the kind of funds move markets that much will also have plenty spare to pay astroturfers to muddy the waters.
Bitstamp's probably the most likely as its the most recent news but after seeing the silkroad "crash" that started before news was even released its obvious headlines are sometimes more an excuse than a reason. Who knows, maybe China banned Bitcoin yet again.