The loss of advertisers, or reduction in spending by advertisers with Facebook, could seriously harm our business;
Growth in use of Facebook through our mobile products, where we do not currently display ads, as a substitute for use on personal computers may negatively affect our revenue and financial results;
Facebook user growth and engagement on mobile devices depend upon effective operation with mobile operating systems, networks, and standards that we do not control;
We may not be successful in our efforts to grow and further monetize the Facebook Platform;
Our business is highly competitive, and competition presents an ongoing threat to the success of our business;
Improper access to or disclosure of our users’ information could harm our reputation and adversely affect our business;
Our business is subject to complex and evolving U.S. and foreign laws and regulations regarding privacy, data protection, and other matters. Many of these laws and regulations are subject to change and uncertain interpretation, and could harm our business.
Of all the risk factors above, the first one and the last two strike me as the most genuine. At some point, Facebook Fatigue could kick in. At the very least, growth eventually will slow.
There's a lot more in the S-1, but I've covered the highlights. I'll probably have more on Thursday, including analyst reaction.