While his family returned to China, he stayed behind and founded ShoeMart, a small Manilla shoe store, in 1958.
Over the decades he developed ShoeMart into SM Investments, one of the largest conglomerates in the Philippines, including 77 SM malls in the Philippines and China, 62 department stores, 56 supermarkets and over 200 grocery stores.
SM also owns Banco de Oro, the second-largest bank in the Philippines, and real estate holdings/For eleven straight years until his death, Sy was named by Forbes as the richest person in the Philippines.
Upon his death on January 19, 2019, his estimated net worth amounted to US$19 billion, making him the 53rd-richest person in the world.