United, who were at the top of the list in 2011 and 2012, remain in fifth position with a value of $3.32billion (£2.53bn).
For the first time since the list’s inception in 2011, a football team is not at the top of the pile with Real Madrid knocked into second after three years at number one.
Their place has been taken by NFL franchise Dallas Cowboys. The Texas-based American football side have been listed as being worth $4bn (£3.04bn) with Real at $3.65bn (£2.78bn) and LaLiga rivals Barcelona just behind in third at $3.55bn (£2.7billion).
Arsenal are the second highest British team, sitting down in 23rd – 13 places higher than last year – having been valued at $2.02 billion (£1.54 billion).
Liverpool have made the top 50 after missing out on last year’s list, are ranked 41st place at $1.55bn (£1.18bn), with Chelsea the only British team to have dropped down in the list, falling five places to 36 at $1.61billion (£1.23billion).
Manchester City were valued at $1.92billion (£1.46bn), taking them up one place to 28th, as Premier League sides accounted for five of the eight football teams in the top 50.
Bayern Munich just missed out on the top 10 in 12th place while eight NBA franchises and 27 of the 32 NFL teams made the top 50.
Forbes magazine’s most valuable sports teams top 10:
1. Dallas Cowboys – $4billion (£3.04billion) – NFL
2. Real Madrid – $3.65bn (£2.78bn) – FOOTBALL
3. Barcelona – $3.55bn (£2.7bn) – FOOTBALL
4. New York Yankees – $3.4bn (£2.59bn) – MLB
5. Manchester United – $3.32bn (£2.53bn) – FOOTBALL
6. New England Patriots – $3.2bn (£2.43bn) – NFL
7. New York Knicks – $3.0bn (£2.28bn) – NBA
8. Washington Redskins – $2.85bn (£2.17bn) – NFL
9. New York Giants – $2.8bn (£2.13bn) – NFL
10=. Los Angeles Lakers – $2.7bn (£2.05bn) – NBA
10=. San Francisco 49ers – $2.7bn (£2.05bn) – NFL