It is the first time that sports giants all made significant losses in their income.
“We estimate that the 20 clubs in the Money League will lose over two billion euros in revenue at the end of the 2020/21 season,” the company stated.
Barcelona have a net worth of 715 million euros, although they lost 125 million euros in the last year.
Bundesliga giants, Bayern Munich are third on the list on 634.1 million euros.
Former Premier League champions, Manchester United are fourth on the list with a net worth of €580m.
The Red Devils lost €135m in 2020, which was a 19% drop in total income from the previous year.
See top 20:
Real Madrid €714.9m
Bayern Munich €634.1m
Manchester United €580.4m
Manchester City €549.2m
Paris Saint-Germain €540.6m
Tottenham Hotspur €445.7m
Borussia Dortmund €365.7m
Atletico Madrid €331.8m
Eintracht Frankfurt €174m