US private equity firm Apollo Global Management is planning to join an auction for the sale of all of GlaxoSmithKline's mature drugs, Reuters reported.
Four people familiar with the process told the news agency that the firm run by Leon Black would be buying all the products on offer, valued at more than $3bn (£1.9bn, €2.4bn), while other bidders are looking to acquire certain regional businesses.
Other potential bidders include private equity firm KKR, which has teamed up with private Dutch-based specialty drugmaker Norgine, and Denmark's Lundbeck.
GSK had asked for final bids by early next week, according to the sources. The company is being advised by Lazard in the sale process and aims to find buyers by the end of 2015.
Appollo's bid, if approved, would make GSK's sale process simpler, as it has to deal with a single buyer.
With a view to streamlining its operations, Britain's biggest drugmaker is working to divest its mature prescription medicine products sold in North America and western Europe. The products include antidepressant Paxil, migraine treatment Imitrex, Zantac for stomach acid and Zofran for nausea.
The drugs are expected to have a combined 2014 sales of around £1bn, but they are facing stiff competition from cheaper generics.
The company would retain the rights to sell the drugs in emerging markets, where they are still growing.
The acquisition is expected to be complicated for private equity firms, as GSK is not planning to sell the factories. The firms would need to outsource manufacturing following the acquisition of the drugs.
Apollo, one of the biggest alternative investment managers in the world, was founded in 1990, and has total assets under management of about $164bn as of 30 September.