The impressive thing is that he waited until FB was over $100 to sell.  Facebook was faced with a huge uphill battle with Wall Street.  Each time they had solid earnings, the stock would go down on fears of young people not using the service or their inability to monetize mobile properly or that they overpaid for Instagram.<p>Wall Street finally caught on that it is a social network in a league of their own and a company that makes solid decisions, but it took a long time and Marc could have easily sold along the way.<p>Andreessen stuck through all of that to make it to $100+.  It seems like he felt like it was time to cash in.  Rightfully so.  FB will be just fine moving forward.