At Oracle, they had two co-CEOs, Safra Catz and Mark Hurd. Catz also fulfilled the role of CFO, so there was a clear division of roles. Of the three companies we are discussing, Oracle seems to be the most suitable for a co-CEO position. This is because Larry Ellison is also very active in the company as founder, CTO, chairman of the board and major shareholder. Ellison could always give a definitive vote if the co-CEOs did not agree on a subject.