Equity ownership of Formosa Petrochemical Corporation is heavily concentrated among its sister companies within the broader conglomerate, with Formosa Plastics Corporation, Formosa Chemicals & Fibre Corporation, and Nan Ya Plastics Corporation holding the vast majority of shares. Additionally, institutional entities such as the Chang Gung Medical Foundation and various public mutual funds hold meaningful equity stakes, while millions of shares trade freely among public investors on the Taiwan Stock Exchange.