The deal is now the first for the company, which has previously announced that it will allocate $5 billion, equivalent to just over 47 billion Swedish kronor, to investments in the world of sports.
The value of the deal has not been announced, but sources told Bloomberg that the club is valued at $2.2 billion. Apollo joins a growing group of venture capital firms that have chosen to invest in football clubs such as Chelsea, Inter and Milan.
Atlético Madrid is currently in fourth place in La Liga, six points behind Real Madrid.
