This is most likely a single entity, and it has spent 10 million dollars just in November
What do you mean? Isn't this just SecondMarket buying?
It is assumed that SMBIT only buys BTC when some client buys their shares (10 shares = 1 BTC). If that is true, there seems to be a client who buys 2.5 million dollars worth of shares each week. But we do not know, really.
I don't really understand why we're assuming that it's a single client. Secondmarket just updates the aggregate figures every week or so, as far as I can see; how are we reading anything about number of clients purchasing into that?
We don't know really, we are just guessing, based on the observation that the recent buys are much larger than usual, they come after a period of stagnation, they started with no obvious external cause, they are almost the same size in USD (but less so in BTC), and the size in USD is a round number (2.5 M$), within the errors of the estimates.
If there were many clients buying shares, why would they all start buying at the same time, considering that the price does not give any clear signs of recovery? Why would their buys add up to ~2.5 M$ every week, four weeks in a row?
It is of course possible that there are no clients buying shares, and SMBIT just decided to but BTC anyway, using their dollar reserves.
Here is another wild theory: the SEC found that they were doing something wrong, ordered them to suspend selling and liquidating shares, and required a change in their procedures -- that forced them to buy a lot more BTC than they had bought so far. So they are buying as far as they can, that being 2.5 M$ every week. (Yeah, it is total fantasy; but since SMBIT is so opaque, they can't complain if people start making wild theories...)