Most founders who take venture money understand, in the abstract, that they are giving up equity. What many do not fully reckon with is the cumulative arithmetic of multiple rounds — and what that arithmetic means for who actually owns the company by the time an exit occurs.

Start with a founder who owns 100% of their company at incorporation. They raise a seed round and give up 20%. They are now at 80%. A Series A follows, with another 25% going to new investors. The founder is at 60%. Series B takes another 20%. Now they are at 48%. An employee option pool, typically 10–15% of the company, was refreshed at the Series B. Call it 45% after dilution from that. The company has grown significantly. The founder still works there. They now own less than half of what they built.