Is A Facebook Co-Founder Selling 10 Million Shares?

Facebook has a policy of not commenting on matters of speculation; so let's talk hypothetically about whether a co-founder wants to sell up to ten million shares of the company's stock.

Rumor has it that one of Facebook’s co-founders wants to sell up to ten million shares of the company’s stock.

We crave substantiation of this rumor, and have asked Facebook for confirmation, knowing full well that the company has a policy of not commenting on matters of speculation. So let’s talk about this whole thing hypothetically, rather than presume it to be true.
Garrett Sloane of the New York Post cites a “source close to the situation” as saying “at least one dealmaker has been approached by reps of the co-founder to unload up to 10 million shares of common stock in Facebook.”
Facebook has four co-founders, and only one of them still works for the company, Chief Executive Officer Mark Zuckerberg. We suspect he’s not the one trying to sell up to 10 million shares, assuming the rumor proves true, of course. A CEO’s best interests lie in propping up the value of the stock, not starting a sell-off in the private market.
The other three co-founders have gone off on their own, and thus seem much more likely to sell stakes, simply to lock in profits. Dustin Moskovitz launched Asana; Chris Hughes started Jumo, and Eduardo Saverin has led the investing in the startup Qwiki. The three each have lower single-digit percentage stakes in Facebook, and one might argue that all would have good uses for the proceeds from selling 10 million shares. The money could fund the expansion of any of their respective business ventures.
Selling 10 million shares wouldn’t liquidate one of the co-founders’ entire holdings of Facebook but rather take off a fraction of a percent, depending on which valuation of Facebook you want to look at. The recent investment led by Goldman Sachs puts the value at $50 billion, while recent transactions on SharesPost and SecondMarket come in around the $60 billion mark.
No matter which number you go with, selling now would make a bundle for any co-founder, assuming such a sale happens. But without official confirmation from Facebook nor any so-called dealmaker, all of this talk about selling shares in the company is simply — well, talk.
Readers, what do you think: Is a Facebook co-founder really looking to sell 10 million shares right now? And if so, what kind of stock price will the transaction have?