The live music company Live nation owns the ticketing site Ticketmaster, which earlier this week left Taylor Swift fans very disappointed.
The system crashed when millions tried to buy tickets at the same time.
But the ticket chaos also drew attention to Live Nation's position of power in the American music industry.
According to American media, the lack of competition in ticket sales has led to high prices and fewer choices.
Something experts warned would get worse when Live nation bought Ticketmaster, writes Business insider.
The New York Times now learns that the Department of Justice is investigating whether Live Nation approached something resembling a monopoly position and could thus violate US competition laws.
Live nation has not commented on the matter.