You are certainly entitled to give up whatever equity you like, and perhaps you are a better man than me for not feeling you deserve such a minor stake. If you feel you did the right thing and fully comprehend the situation, it is not my place to challenge your decision. I'm only expressing my thoughts, and my feeling that this is not the way to handle pivots with former co-founders anymore than it is a way to handle pivots with investors.

I don't know how long and hard you worked, how related your work was to the ultimate direction, whether you participated in early fundraising, advised the continuing founders, etc. All of those could impact my thoughts on this. Going on the assumption that you worked long and hard - you contributed to the ultimate direction and team and you earned something.

"Pivots" are all the rage in startups these days. Why is it any more acceptable to ask for vested founder shares to be returned than to ask for shares to be returned from early cash investors or advisors? Does YC return shares to founders who pivot after leaving YC?

I think it can be fair to renegotiate stakes according to impact, as it appears you did to get down to 0.5%, but eliminating clearly earned stakes entirely seems rarely justified. Re-incorporation makes sense in many cases, but in others will open the new company to accusations of fiduciary violations largely for the same reasons.