Single-Trigger Acceleration
Accelerated vesting triggered by just one event, usually an acquisition, regardless of employment status.
Definition
Single-trigger acceleration causes all (or a portion of) unvested equity to vest immediately upon a single event, typically the acquisition of the company. Unlike double-trigger, the employee does not need to be terminated. Single-trigger is more employee-friendly but less common because acquirers dislike it, as it removes the retention incentive for key employees post-acquisition.
Why it matters
If you have single-trigger acceleration and your company is acquired, all your unvested equity vests immediately, regardless of whether you keep your job. This is the best-case scenario for employees but is rare outside of executive packages.
Example
A VP has single-trigger acceleration on 100,000 unvested options. When the company is acquired for $500M, all 100,000 options vest immediately. They can exercise and sell, pocketing the full value without needing to stay at the acquirer.