Facebook

The Facebook IPO is making dozens of people phenomenally rich. How rich? Check out CNBC's list of top shareholders, see and the amounts of their Facebook windfalls as they move based on the real-time price of the shares.

For your reading pleasure while you watch the roller coaster ride of Facebook's Friday trading debut, here's a list of facts about the company and CEO Mark Zuckerberg that aren't widely known.

GM's ill-timed announcement that it will no longer advertise on Facebook should come as no surprise. The site is popular. Its paid ads aren't. Only about 1 in every 2,000 ad impressions on the social media giant received clicks for advertisers.

Facebook insiders will be unloading more of their shares in the initial public offering, the company said Wednesday, as they take advantage of investor demand. The entire increase comes from insiders and early investors, so the company won't benefit from the additional sales.

Don't feel bad that you aren't one of those lucky, well-connected investors who gets to buy into Facebook's IPO this week. Those buyers may look lucky when the likely initial price pop happens. But odds are, the pop will be followed by a drop.

General Motors has pulled $10 million in ads from Facebook because they just didn't work, according to The Wall Street Journal. GM is the first major advertiser to indicate disappointment with Facebook and reduce its ad spending on the site.

Faced with great expectations, Facebook is staring down some potentially unnerving obstacles when it comes to key areas of monetization and growth: public distrust and display advertising apathy.