Nov 15 (Reuters) - Warren Buffett"s Berkshire Hathaway Inc (BRKa.N) said on Monday it eliminated its investment in Merck & Co (MRK.N) and reduced its stakes in Abbvie Inc (ABBV.N) and Bristol-Myers Squibb Co (BMY.N), as it pared its overall stock market investments. The changes were disclosed in a regulatory filing detailing Berkshire"s U.S.-listed holdings as of Sept. 30. Berkshire also disclosed new investments in Royalty Pharma Plc (RPRX.O), which buys pharmaceutical royalties, and flooring retailer Floor & Decor Holdings Inc (FND.N).