Sony/ATV Music Publishing, owned by Sony and Michael Jackson's estate, submitted a bid for Warner Music Group ahead of yesterday's deadline.
Unnamed sources said Sony/ATV made a joint bid with billionaire Ronald Perelman and Guggenheim Partners.
Warner Music yesterday called a board meeting with the aim of picking a buyer in 48 hours.
The entry of Sony/ATV increases the number of known bidders to three after billionaire investor Ron Burkle decided to walk away last week.
Len Blavatnik, a former Warner Music director, and brothers Tom and Alec Gores also submitted bids ahead of the deadline.
Sony/ATV's bid is in the US$3 billion ($3.7 billion) range offered by Blavatnik and the Gores brothers.
The company, headed by Martin Bandier, is interested in Warner Music's publishing business, while its partners are focused on recorded music, a source said.
There was no comment from four of the parties involved in the bids.
The record company, home to artists including Cee Lo Green and the Black Keys, has long-term debt of US$1.94 billion, according to company filings.
Eight of Warner Music's 13 directors are executives of Thomas H. Lee Partners and Bain Capital, two Boston-based private-equity firms that together hold 51 per cent of the company's shares, according to data compiled by Bloomberg.
Providence Equity Partners owns 8.3 per cent and chairman and chief executive Edgar Bronfman jnr owns about 7 per cent.