The common stock issued to founders at incorporation, priced at a fraction of a cent and almost always on a reverse vesting schedule so a founder who walks early gives most of it back.
When Apple incorporated in 1977, Steve Jobs and Steve Wozniak each held forty-five percent of the founder shares and Ronald Wayne held the remaining ten. Wayne sold his stake back to the other two for $800 twelve days after incorporation, a slice that would have been worth tens of billions by the company's later peak. The episode is the textbook case of why founder allocations and vesting matter from day one.