conclusion, your prediction is impossible
Could it be be a client with special privileges? Like, someone inside MtGOX and/or Bitstamp?
Arbitrage trading requires the ability to transfer cash or coins quickly between markets. One way, as the poster suggested, is to have a pile of coins and a pile of cash in each exchange. Then one can do instantaneous "virtual transfers" if required by the chosen arbitrage strategy, and do real transfers later, once in a while, only to rebalance the piles. Does this make sense?
again there is no one special with more "privileges" over the bitcoin protocol, such thing doesn't exist, as simple as this. please read more about the technical aspect of Bitcoin because this is what makes Bitcoin special and the rocketing price that jumps from $13 to $1240 is because of people realizing the "technical phenomena" bitcoin is....
I think everyone should spend more time educating them selves about bitcoin before heavily investing, the last couple of months proved that people just jumped with their cash into bitcoin thinking of it as a quick get rich scheme, some people doesn't believe in bitcoin but in the potential income from it.. this is why we see people panicking....
I didn't invest a single dollar when I first knew about Bitcoin, I took all time I needed before deciding and asked all "stupid" question until I felt that I have a good understanding.