Some startups are changing the exercise window for stock options from 90 days to something longer. This helps employees who can’t afford to exercise their options if they leave (golden handcuffs). However there is a downside to existing employees: moving from a 90-day to a 10-year window costs the average remaining employee as much as 80% in incremental dilution.
Increasing the dilution of existing employees who are the ones increasing the value of the company creates a further imbalance between early employees who have a much greater equity stakes and current employees.
Read The Lack of Options for (Startup Employees’) Options from a16z.