Real Madrid has overtaken Manchester United as the world's most valuable football club, according to business magazine Forbes.It is the first time that Man Utd has lost the top spot since Forbes first started compiling its list in 2004.Forbes now values the Spanish giant at $3.3bn with Man Utd in second place on $3.17bn. Barcelona is third. $2.6bn. Forbes found that Arsenal was the fourth richest club, worth $1.33bn, followed by Bayern Munich ($1.31bn), AC Milan ($945m), Chelsea ($901m), Juventus ($694m), Manchester City ($689m) and Liverpool ($651m).Forbes says Real Madrid was financially successful in spite of the continuing woes of the Spanish economy.In coming to its figures, Forbes looks at a football club's various revenue streams, such as television money, ticket sales, merchandise and concessions.David Beckham, now with French team Paris St-Germain, was the highest earning player, followed by Real Madrid's Ronaldo.