Daiichi Sankyo Europe, GmbH (DSE), the European subsidiary, is headquartered in Munich, Germany.

On June 10, 2008, the company agreed to take a majority (64%) stake in Indian generic drug maker Ranbaxy, with a deal valued at about $4.6 billion.

[16] The acquisition of Plexxikon, a Berkeley, California-based pharmaceutical start-up company, was completed on April 4, 2011, for $805 million and an additional $130 million in milestone payments, pending on the success of Vemurafenib (Plexxikon's lead program) an oral, novel drug that targets the oncogenic BRAF mutation present in about half of melanoma cancers and about eight percent of all solid tumors.

[17] The shutdown of Plexxikon was announced in 2022[18] as Daiichi Sankyo pivots to focus on more antibody-drug conjugate therapies.

[21] It transferred 41 of its products in Japan to Alfresa Holdings Corporation for JPY 4.2 billion in 2018 in order to focus on oncology.

[23] In January 2020, the company's market value rose above JPY 5 trillion after the U.S. Food and Drug Administration approval and release of Enhertu,[24] an antibody-drug conjugate for cancer treatment.

[28] “Manufacturers and physicians who engage in them are cheating Medicare and Medicaid out of millions of dollars and threatening programs upon which many elderly and disabled Americans rely.