If I'm not mistaken, the Washington Redskins are the most "valuable" sports franchise. In fact according to Forbes, the Yankees are about the 15th or 16th most valuable sports franchise (from memory)... BTW all the teams ranked before them are NFL teams with the Cowboys and Texans rounding out top 3.
Not quite. Yanks are fifth on the list, behind Man. United, Cowboys, Redskins and Patriots.
http://www.forbes.com/2009/01/13/nfl-cowboys-yankees-biz-media-cx_tvr_0113values.html