Vesting Acceleration

A clause that causes unvested equity to vest immediately upon a triggering event — most commonly an acquisition — protecting employees from losing unvested shares when a company is sold.

Vesting acceleration is a contractual provision that causes some or all of an employee's unvested equity to vest immediately upon a defined triggering event, rather than following the normal vesting schedule. It's most commonly relevant in the context of mergers and acquisitions: without an acceleration clause, an employee with 2 years of unvested equity remaining who is acquired — and then fired by the acquiring company shortly after — may lose that unvested equity entirely. Vesting acceleration protects employees from exactly this scenario.

There are two main types of vesting acceleration. Single-trigger acceleration causes vesting to accelerate upon the occurrence of a single event — most commonly a change of control (acquisition or merger) itself, regardless of whether the employee is retained or terminated. Double-trigger acceleration requires two events to occur: (1) a change of control, AND (2) a qualifying termination (being laid off or constructively dismissed without cause within a defined period, typically 12–18 months after the acquisition). Single-trigger is more valuable to employees (acceleration happens regardless) but less common, because it removes an incentive for acquiring companies to retain key employees. Double-trigger is the more standard provision and is broadly accepted as employee-protective without creating the retention alignment problems of single-trigger.

Not all employees have acceleration provisions in their equity grants — historically, acceleration clauses were primarily negotiated by executives and senior engineers. But awareness of these provisions has grown, and many companies now include some form of double-trigger acceleration in their standard option and RSU grant agreements for employees at director level and above. For earlier-stage employees and those in non-senior roles, acceleration is less common in standard grants but sometimes negotiable at the offer stage, particularly in competitive hiring situations or when an employee is joining a company that is already a known acquisition target.

Single-Trigger vs. Double-Trigger Acceleration

  • Single-trigger: all or a defined portion of unvested equity vests immediately upon a change of control (acquisition), regardless of what happens to the employee's employment. More employee-favorable; less common in standard grants.
  • Double-trigger: equity accelerates only if BOTH a change of control occurs AND the employee is terminated without cause (or constructively terminated) within a defined post-acquisition window (usually 12–18 months). Standard in most executive agreements and increasingly common for senior employees.
  • Partial acceleration: some grants accelerate only a portion of unvested equity (e.g., 50% or 100% of the 'next 12 months' worth of vesting). More common than full acceleration for non-executives.
  • Change of control definition: read how your grant defines 'change of control' — it typically means an acquisition of 50%+ of voting shares, a merger where existing shareholders end up with minority ownership, or an asset sale of substantially all assets.
  • Qualifying termination: double-trigger requires a 'qualifying termination' — typically 'without cause' or 'for good reason' (which usually means material reduction in responsibilities or pay, relocation requirement, or breach of the employment agreement).
  • Where to find it: your equity grant agreement (separate from your offer letter) specifies your acceleration provisions. Ask your stock plan administrator or legal team if you're unsure.

What to Do If Your Company Is Being Acquired

When an acquisition is announced, equity holders should take several steps. First, locate your grant agreements and understand exactly how many shares are unvested, what your acceleration provisions (if any) say, and what the acquisition structure means for your equity (cash deal, stock-for-stock, or combination). In cash acquisitions, unvested equity is often either assumed by the acquirer (with new vesting terms), accelerated per contractual provisions, or paid out at the acquisition price but subject to the original vesting schedule. In stock-for-stock deals, equity is typically converted to the acquirer's shares on equivalent terms. The treatment of unvested equity in an acquisition is disclosed in the acquisition documents — request a summary from your company's legal or HR team, as the details significantly affect your financial outcome. If you have double-trigger acceleration and are subsequently laid off, triggering the second event, ensure the acceleration is recognized and document the timing carefully.

Example

A senior engineer has 10,000 unvested RSUs from a grant made two years ago at a $20 fair market value, currently worth $35/share. Her company is acquired. Her grant agreement includes double-trigger acceleration: 100% of unvested RSUs accelerate if she's terminated without cause within 18 months of the closing. Six months after closing, the acquirer lays off her team. The double-trigger conditions are met: acquisition (trigger 1) + termination without cause (trigger 2). All 10,000 unvested RSUs accelerate and vest immediately. At the acquisition price of $35, she receives $350,000 in accelerated equity that she would have lost had she not had the double-trigger provision.