I would try reading your agreement, it usually plainly talks about what its restrictions are. For instance a very common clause is called "first option" (don't

I would try reading your agreement, it usually plainly talks about what its restrictions are. For instance a very common clause is called "first option" (don't quote me on these names, not 100% certain they are correct), in order to sell the stock you must first offer the company the stock at the same price. An alternative (probably the one in the Uber example here) is "first option at market" where in order to sell you must first offer to sell to the company at the market rate ("helpfully" determined by the company).