With the stock market hitting all-time highs, many investors have been thankful for 2013. In the following video, Motley Fool analysts David Hanson, Matt Koppenheffer, and Morgan Housel tell viewers why they are specifically thankful for PNC, Markel, Facebook, Twitter, and LinkedIn. While the group has a rosy outlook for some of these stocks, all three point to broader business themes as reasons to be thankful.