On Dec 5 between 8am and 10am, roughly $15MM worth of BTC were sold. Someone bought those, and someone's numbers in a computer reflect it -- but I'm highly curious where the $15MM in actual money is residing, since MtGox doesn't seem to be able to put their hands on that much in any reasonable timeframe, and that chart pulls from MtGox.
According to what we've been told here and what I've read, someone (well, a lot of different someones obviously) had to have deposited $15MM in an account to make those purchases. But the MtGox withdrawal options are all painfully staggered so that it's trivial to put cash in, but very hard to get cash out. I'd sure like to know what the problem is there -- as well as all those other exchanges that Beelzebuddy appears to be trying to use to liquidate his own gains.