The Competition and Markets Authority (CMA) is to assess Hasbro’s acquisition of Entertainment One.
The proposed $4 billion (£3.1bn) deal would include eOne’s music division. Hasbro made the offer for the company in August.
The music division includes artists and labels Death Row, Wu-Tang Clan, Snoop Dogg, The Game, Emily Haines, Tiga and Soulja Boy.
The CMA is considering whether the acquisition would substantially reduce competition in the UK.
The competition watchdog is inviting comments on the transaction from interested parties. The deadline is December 5.