Aug 16 (Reuters) - Warren Buffett’s Berkshire Hathaway Inc said on Monday it has shed its holdings of drugmaker Biogen Inc and paint maker Axalta Coating Systems Ltd , while taking a new stake in another pharmaceutical company, Organon & Co. The changes were disclosed in a regulatory filing detailing Berkshire’s U.S.-listed holdings as of June 30. Berkshire has been a net seller of stocks in 2021, including in the second quarter. The sales suggest that Buffett and his investment managers Todd Combs and Ted Weschler are wary of valuations as stocks regularly set new highs. Reporting by Jonathan Stempel in New York, Editing by Rosalba O’Brien Our Standards: The Thomson Reuters Trust Principles.