Example of this happening IRL? I've seen right of first refusal and tag along rights that make it harder to find a buyer, but nothing that actually prevents sale of vested shares.
As I understood the few contracts I've had they barred me from selling to anyone unless the company approved. That in practice meant I had no liquidity unless IPO or got to sell to investors in the next fund raise round (very very rare).
And think about it a bit further, who's going to go through any due diligence if their research and offer is going to first hit the board/company and potentially completely vanish for them? I certainly wouldnt invest time/resources to see if I wanted to buy shares from an employee to potentially find out the company decided to buyback those shares instead. This property would massively lower the price I'd be willing to offer. (as a compensation for my risk taken)
Example of this happening IRL? I've seen right of first refusal and tag along rights that make it harder to find a buyer, but nothing that actually prevents sale of vested shares.