Boston-headquartered Advent had tapped JPMorgan to advise on the potential sale of its stake, said two of the people, adding that the bank had contacted potential buyers to gauge interest.
A formal sale process, however, may not kick off until next year, said one of those two sources.
Bioduro-Sundia operates in the United States and China, with more than 2,000 employees and 10 facilities, providing contract research, development and manufacturing outsourcing services, according to Advent's website.
Advent is looking to sell its stake in Bioduro-Sundia at a company valuation of more than 20 times annual earnings before interest, tax, depreciation and amortisation, said the second source. The valuation would be more than $1 billion, that person said.
The seller could be seeking a valuation as high as $1.5 billion, said the third source.
All the sources declined to be identified, because the information was confidential. Advent, Bioduro-Sundia and JPMorgan declined to comment.
Advent bought a majority stake in San Diego, California-based Bioduro in 2019 and a year later merged the company with peer Sundia. Financial details of those two transactions have not been disclosed, nor has the exact size of Advent's holding.
Bioduro-Sundia has provided drug research services for major pharmaceutical firms in China, including Shanghai Fosun Pharmaceutical Group and InnoCare Pharma, Bioduro-Sundia says on its website.
It has also worked with Pfizer to develop a drug-making compound called AISF, the company says.
(Reporting by Kane Wu in Hong Kong and Roxanne Liu in Beijing; Editing by Bradley Perrett)
By Kane Wu and Roxanne Liu