The answer is (effectively) none.<p>In other words, for a typical $15mm exit, as an employee (meaning no preferred stock, and thus subject to a 50% tax rate on exit), you need to own ~13.33% of the company (pre-dilution, and thus, pre-Series A employee) to net $1mm and make you a millionaire. Of course, most companies go through plenty of dilution. If typical dilution is half, you therefore would realistically need to own more than 25% of a company to net $1mm on a $15mm exit.<p>No employee receives 25% equity of a company - <i>single founders</i> are lucky to have 25% when they exit. First hires / founding team are lucky to get between 2-5%. Assuming 3.33% (which is still high), dilution and taxes, you're now looking at a $120+mm exit to become a millionaire as employee #1.<p>What is the likelihood a company exits for $120+mm? For YC companies, 10% have exited (54 out of 548 according to YC List). Of that, only 3 have ever exited over $120mm, which represents ~0.5% of all YC companies. Many are still active and valued over $100mm, such as AirBnb and Instacart, but again, since they haven't exited in your 4 year time slot assigned to the problem, we can't say what they will be worth, or if they will even exit or IPO in the next 4 years.<p>So if you manage to land a first employee spot at a coveted YC startup, you have less than a 1% chance of becoming a millionaire in four years from that company. So your typical startup after series A is virtually impossible by the odds. Therefore you either need to (1) start a company or (2) earn a high enough salary (or mixed income sources) to save aggressively that you can be a millionaire in that time.