武田薬品工業
OPC's parent company Otsuka Holdings Co. Ltd. joined the Tokyo Stock Exchange through an initial public offering (IPO) on December 15, 2010, at which time Otsuka Holdings was Japan's No.2 drug maker by sales after industry leader Takeda Pharmaceutical Company. The IPO debuted at $2.4 billion, making it the largest for a pharmaceutical company up to that time.