[1] What is the CEO's cliff and vesting? [2] Longer vesting means more stock, around 50% in this case, for companies who want employees long-term. (The relevant measure is stock/year, not total stock.) [3] Ask the CEO to name three comparable companies with such terms.

If there's a hostile reaction to [3], you just learned something valuable. If there's a neutral reaction, you can say that you're evaluating the CEO's ability to negotiate and persuade, which is true.

Interviews and offer negotiations go both ways.