Complex sentence: It is the world's largest owner of sports teams and sports events, the owner of the world's most profitable sports and entertainment venues, and under AEG Live, the world's second largest presenter of live music and entertainment events (after Live Nation).
Split into simpler sentences: It is the world's largest owner of sports teams and sports events. Under the AEG Live brand, it is the world's second largest presenter of live music and entertainment events (after Live Nation).