[lancewiggs]

Others have talked about your legal (just no) and not-so-legal (a quiet side agreement) avenues.

Another approach is to try to push the issue harder with the controlling shareholders and Board.

Perhaps get together with your peers who also have non-transferrable stock, and even with the founders if they are in the same boat. If there is enough demand for sale, especially from current staff who are critical to the business, then you have a lot more bargaining power with the Board/lead investors.

Meanwhile if you can really get enough people (or $) interested in buying shares then the amounts at stake will be increasingly be material enough for the Board to take notice.

Smart investors would allow the shares to be traded (as secondaries), as keeping staff and former staff happy is smart long term. Not allowing trading devalues also the value of new options being issued to current staff, and I've seen later stage smarter firms blow up these rules and allow for share sales.