Now that Facebook is fast on its way to becoming a public company, and its financials have been laid bare, there’s just one question that remains unanswered: What is Facebook actually worth?

A private market transaction completed Thursday may provide us with best the answer yet.

One hundred thousand Class B common stock shares were sold for $40 a pop on SharesPost, according to information obtained by Bloomberg News and confirmed by the private capital market. The sale, factoring in a fully diluted total share count of 2.35 billion, values the social network at $94 billion.

Facebook filed to become a public company Wednesday, and it hopes to raise $5 billion in its initial public offering later this year. The company, which touts 845 million monthly active users and an extremely profitable advertising business, could be valued between $75 and $100 billion on its stock market debut.

But the $100 billion figure is fairly optimistic, says one Internet IPO expert.

“The $100 billion number that has been circulated so widely … is all based on 5 percent of the shares being worth potentially $5 billion,” Peter Adriaens, a professor of entrepreneurship at the University of Michigan’s Zell Lurie Institute for Entrepreneurial Studies, said in an interview with VentureBeat yesterday. “You can’t just apply a multiplier using 5 percent of the shares.”

Of course, speculation as to what the social networking company is actually worth will continue to run rampant leading up to and even following its IPO, especially considering that Facebook has veiled the important particulars behind its prized money-maker.