Revenue pressures for Facebook after IPO

For all the huge numbers in Facebook's IPO papers, a surprisingly small figure stands out: $4.39, the amount of revenue the site generated per user last year.

It's one of the company's major challenges because the total is paltry compared with competing Internet companies. Google makes more than $30 a year from each registered user. Even struggling Yahoo and AOL make $7 and $10, respectively.

Once Facebook goes public, Wall Street will surely demand more. That means the social network will almost certainly have to attract a lot more users or be more aggressive with its advertising, perhaps by mining personal data even more than it does now.

But can Facebook do all that without spoiling the user experience?

The company may have a tough time increasing the number of ads on a site that has become primarily a home for online conversations.

"It's a communications tool. Can you imagine what a turnoff it would be if we were talking on the phone and AT&T tried to play an ad in the middle of our conversation?" said University of Notre Dame finance professor Tim Loughran, who studies IPOs.

Facebook stock probably won't begin trading until at least May, but analysts already believe the company will try to sell shares at a price that will give it a market value of at least $100 billion -- more than Yahoo, AOL and Hewlett-Packard Co. combined.

To justify a valuation like that, Facebook will need to maximize its revenue to get closer to Google, one of its biggest rivals. Google's revenue of nearly $38 billion last year translated into about $35 per registered user.

Facebook's IPO prospectus filed Wednesday shows it generated $3.71 billion in revenue and made $1 billion in net profit last year, up 65 percent from the $606 million it made in 2010.

What he'll be worth

How much will Mark Zuckerberg be worth when Facebook goes public? The 27-year-old founder and CEO is the company's top stakeholder, with 533.8 million shares, or 28.4 percent, according to a regulatory filing. Analysts expect Facebook to be valued at $75 billion to $100 billion in the sale. At the top end of that range, Zuckerberg will own stock worth $28.4 billion.