Eusebio H. Tanco is chairman of the 11-person board of STI Education Systems Holdings Inc., which uses STI for its company symbol. As of March 31, 2018, he directly and indirectly owned 1,467,017,875 STI common shares, which were equivalent to 14.81 percent of 9,904,806,924 outstanding common shares. He divided his total holdings into direct and indirectly owned 1,253,666,793 STI common shares, or 12.657 percent, and 2.514 percent, respectively.
In its public ownership report (POR) two years ago, the outstanding STI common shares, which carry P0.50 par value, are also listed on the Philippine Stock Exchange (PSE). Their being listed as early as two years ago, until today, makes them publicly traded. (STI means Systems Technology Institute.)