When Thailand's stock exchange recently rejigged its SET50 Index, an index of the biggest companies by market cap, Adisak Sukumvitaya emerged a winner. Admitted were his flagship company Jay Mart plus its debt collection and management unit JMT Network Services, both among the hottest Thai stocks in the past year—up 54% and 74%, respectively—while the index fell more than 3%. The double-entry was a seminal event for the Jay Mart founder and CEO, who opened his first shop, selling household appliances, in 1989.