I recently sold my startup. Oh yeah! The deal was much harder than I expected because the deal's tems required me to get 100% of shareholders to agree to the buyout. Those shares I issued early all on in my startup's life felt like serious baggage towards the end. The deal had a deadline, and one guy didn't decide to sell until 6:00 a.m. of the day the deal was set to expire. It was stressful to say the least.
This is why you usually work in a drag-a-long clause in your shareholders agreement, ours for instance requires everyone to sell if more than some percentage of the shareholders agree.
It prevents a minority shareholder from holding up or killing a deal.