Equity Acceleration Explained: Single vs Double Trigger

An acceleration clause converts unvested equity into vested equity early, on a defined event. In practice that event is almost always an acquisition.

It exists because of a structural unfairness: you join a company at year one, it is acquired at year two, and without acceleration half your grant is still unvested. The acquirer now controls whether you keep it, and the answer frequently depends on whether they want you to stay.

Single trigger

Acceleration on the acquisition alone. The deal closes; your unvested equity vests.

Employees like it. Acquirers dislike it intensely, because it removes the retention value of the equity on the day they need retention most — everyone gets paid and can leave. Companies therefore grant it sparingly, usually only to founders and sometimes only partially.

Double trigger

Two things must happen: the company is acquired, and you are terminated without cause or resign for good reason within a window after closing — typically twelve months.

This is the market standard for employees, and it is a genuinely sensible compromise. If the acquirer keeps you, your equity keeps vesting on schedule. If they get rid of you, you are not penalized for an outcome you had no part in.

The wording that decides whether you actually qualify

Double trigger is only as good as its definitions, and this is where the drafting does the work.

"Good reason" must include a constructive dismissal. Without it, the acquirer can move you to a worse role in another city at lower pay until you resign — and a resignation is not a termination, so nothing accelerates. Look for good reason to cover:

• A material reduction in salary or target bonus
• A material diminution of duties, title or reporting line
• Relocation beyond a stated distance
• A material breach of your agreement by the employer

The window must be long enough. Six months is short; twelve is standard. Some agreements also cover termination in the period before closing where it was at the acquirer's request — worth having.

"Cause" must be tight. If cause is defined widely enough to cover ordinary performance issues, the acquirer can terminate for cause and avoid acceleration entirely.

How much accelerates? Full acceleration vests everything. Partial acceleration vests a defined portion — 50%, or "twelve months of additional vesting". Partial is common below executive level.

What acceleration does not protect you from

A deal where the equity is worth nothing. Acceleration on a liquidation preference stack that pays out entirely to preferred shareholders accelerates a zero.

Cancellation and replacement. Many acquisitions convert your options into acquirer options or into a retention package on a new schedule. Check whether your agreement requires assumption on equivalent terms, or permits substitution on whatever terms the acquirer chooses.

The exercise problem. Accelerated options still need exercising, still cost money, and are still subject to the post-termination window. Acceleration without an extended window can leave you with a large tax event and a short deadline.

What to ask for

At senior level, this is a reasonable and commonly granted package:

Double-trigger acceleration: 100% of unvested equity vests if, within twelve months following a Change of Control, the Employee's employment is terminated without Cause or the Employee resigns for Good Reason, where Good Reason includes a material reduction in compensation, a material diminution of duties, or relocation of the Employee's primary work location by more than 50 miles.

Below senior level, ask for double trigger with twelve months of additional vesting rather than full acceleration, and raise it alongside the rest of your offer review. It is a much easier concession to obtain and still meaningful.

FAQ

What is the difference between single and double trigger acceleration?

Single trigger vests your unvested equity on the acquisition alone. Double trigger requires the acquisition and your termination without cause (or resignation for good reason) within a window afterwards. Double trigger is the standard for employees; single trigger is largely reserved for founders.

Is acceleration standard in employment contracts?

Double-trigger acceleration is standard for executives and common for senior employees at venture-backed companies. It is far less common for junior staff, and it usually lives in the equity plan or grant agreement rather than the employment contract itself.

What does good reason mean in an acceleration clause?

It is the set of circumstances in which your resignation counts as a termination for acceleration purposes — typically a material pay cut, a material demotion, or a forced relocation. If your clause has no good-reason definition, the protection is much weaker than it looks.

Does acceleration apply if the company is acquired and I keep my job?

Under double trigger, no. Your equity continues vesting on its original schedule, or on whatever the acquirer assumes it into. Acceleration only fires if you also lose the role.

Can I negotiate acceleration into an offer?

Yes, and the offer stage is the only realistic time. It costs the company nothing today, which is why it is one of the more obtainable equity asks — particularly the partial version.

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