I very much disagree with Mark's assessment. You shouldn't compensate this person for the COO role until they are confirmed into this role and working full-time in this capacity. If they are a part time medical advisor, they should have a very small amount of equity to begin with. It would depend mostly on how much (if any) you've raised to date, but it would be unusual for an advisor to have more than 1% of the Company.

Happy to talk to you about the details of your situation to come up with a fair offer that doesn't hurt your chances of raising capital in the future.

Kind of tough to answer based on limited info. But it will be a significant percentage of the business.

I would expect he should end up with 75% of the ownership you have. (i.e. you have 1MM shares he would have 750K), but at the end of the day it is whatever the two of you negotiate.

Depending on how key this individual is to the company's success, the answer is likely to be in the mid single digit percentage points. For example, he may end up owning 5% of the company in stock options.

But since he is working for equity, you need to compensate him for not taking a salary too. I usually calculate this by figuring out how many shares his salary would have bought him if he'd invested his salary in the company (which is really what he is doing). Then, to compensate for the illiquidity of stock versus cash (salary), I up the result by 50% or perhaps a factor of 2. While there's nothing scientific about this calculation, it has worked well for me in the past.

Stock or options in lieu of salary should vest on a monthly schedule, as if salary were being paid, and there should be no cliff.

Stock or options given as an incentive (not as a substitute for taking a cash salary) should vest over 3 or (preferably) 4 years, and there should be a 1 year cliff to weed out employees who don't hang around or don't work out.