Manchester United has been named as the most valuable club in sport by Forbes Magazine - valuing Sir Alex Ferguson's side at $2.23 billion.
Real Madrid was named second at $1.88billion, Barcelona was eighth at $1.31 billion, while Arsenal was tenth with an estimated value of $1.29 billion.

The List:

#1 Manchester United ($2.23 billion){United 4 lyf }

#2 Real Madrid ($1.88 billion)

#3 New York Yankees ($1.85 billion)

#3 Dallas Cowboys ($1.85 billion)

#5 Washington Redskins ($1.56 billion)

#6 Los Angeles Dodgers ($1.4 billion)

#6 New England Patriots ($1.4 billion)

#8 Barcelona ($1.31 billion)

#9 New York Giants ($1.3 billion)

#10 Arsenal ($1.29 billion)

http://www.forbes.com/sites/kurtbadenhausen/2012/07/16/manchester-united-tops-the-worlds-50-most-valuable-sports-teams/