From Longman Business Dictionary
stockholderstock·hold·er /ˈstɒkˌhəʊldəˈstɑːkˌhoʊldər/ noun [countableC] especially American EnglishAmE FINANCE a person or organization that owns shares in a particular companySYN SHAREHOLDERHe believed that such a large stockholder is entitled to some board seats.
→ controlling stockholder → minority stockholder