I'm seeing a few companies with significant (15% - 20%) employee stock options. In some of these the stock options are mostly already vested. The obvious risk here is the attrition of key talent post purchase given that the employees cash out on their options.

Are there any deal structures that can mitigate the talent attrition risk for the buyer? One of the ideas I have heard is the employee stock payout over 2-4 years post acquisition but I'm not sure if employees will be happy to wait another 2-4 years after already waiting for 4 years (typical vesting schedule).

I would love to hear from the community if there are any suggestions to mitigate this risk.