Manchester United dropped from second to fourth place in the year, overtaken by Barcelona, which rose to second, and Arsenal.
The study said Real turned over €407 million, up from €366 million the previous season. La Liga and Champions League winner Barcelona earned €385 millio. Arsenal's €357 million revenues were boosted by £88 million from the sale of property on the site of its hold stadium, Highbury. Premier League champions Manchester United earned €317 million.
The study also showed that transfer spending by clubs in the top European leagues in the January transfer window fell 66 per cent to €112 million between 2009 and 2010.
