Equity & options

Acceleration (single and double trigger)

Also called double trigger acceleration, single trigger acceleration, accelerated vesting

Acceleration vests equity early when defined events occur: single trigger vests on a change of control alone, while double trigger requires both a change of control and the holder losing their job.

Single versus double trigger

Single trigger vests some or all unvested equity the moment the company is acquired. It is rare beyond founders and senior executives, because acquirers dislike it: the people they are buying become fully vested and free to leave on day one.

Double trigger requires two things. The company is acquired, and within a defined window, usually twelve months, the holder is terminated without cause or resigns for good reason. It protects against being fired after an acquisition while preserving the acquirer's retention incentive.

Double trigger is the market standard for founders and executives. Rank-and-file employees frequently have no acceleration at all.

What to check in the drafting

The definition of good reason does the real work. A meaningful definition covers a material reduction in role, pay or scope, and relocation beyond a stated distance. Without it, an acquirer can make a role untenable without ever triggering acceleration.

Also check how much accelerates. Full acceleration vests everything; partial acceleration vests a fixed portion, often twelve months of additional vesting, which is a common compromise.

Worked example

A founder holds 4,000,000 shares on a four-year schedule, 24 months elapsed, so 2,000,000 unvested.
The company is acquired in month 24.
Single trigger, full: all 2,000,000 vest at closing regardless of what happens next.
Double trigger, full: nothing vests at closing. If the founder is terminated without cause in month 30, all remaining unvested shares vest then.
Double trigger, 12-month partial: on that termination, 1,000,000 shares vest and the rest are forfeited.

Common questions

Is single or double trigger better for founders?

Single trigger is more favourable in isolation, but acquirers resist it and it can reduce the price or complicate a deal. Double trigger with a well-drafted good-reason definition is the standard and usually the realistic ask.

What counts as good reason?

Typically a material reduction in responsibilities, title or compensation, or a required relocation beyond a stated distance. The precise definition matters more than the headline term.

Do employees usually get acceleration?

Most do not. It is normally reserved for founders and senior executives, though some companies extend partial double-trigger acceleration more broadly.

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