Single Trigger Acceleration

Single trigger acceleration is the vesting structure where unvested shares vest upon a single trigger event (typically a change of control), regardless of subsequent employment. The holder receives full value of their grant at close whether or not they remain employed by the acquirer, generally considered the more holder-friendly (and acquirer-unfriendly) of the two main acceleration structures. It is the structure that maximizes equity-holder value at exit and the structure that's hardest to negotiate because it removes acquirer retention leverage and (when applied broadly) can materially reduce deal prices.

The mechanic of single trigger:

• Trigger event: typically defined as a change of control (acquisition of >50% of voting power, merger where existing stockholders own less than majority of surviving entity, sale of substantially all assets). Specific definition varies by agreement.
• At close: defined portion of unvested shares vests immediately. 25%, 50%, or 100% are typical; full single-trigger of 100% is rare.
• Post-close: holder owns the accelerated shares fully (subject to any holdback/escrow that applies to all selling stockholders); the holder may or may not remain employed by the acquirer.

Why single trigger is unfriendly to investors and acquirers:

• Removes retention lever: at close, the executive is fully vested and can leave freely. The acquirer loses the time-vesting leverage that would have kept the executive engaged through transition.
• Increases acquirer cost: acquirers know they'll need to grant new equity (replacement RSUs, retention bonuses) to retain executives who accelerated, on top of the deal price already paid. This typically gets reflected in lower deal prices.
• Misaligns incentives: the executive's incentive shifts from "make the company succeed long-term" to "get to a sale quickly." This concerns investors who want long-term value creation, not transactional thinking.

When single trigger is acceptable:

• Founders with strong negotiating position: at hiring, especially in competitive recruiting environments, founders sometimes successfully negotiate single-trigger 25-50% (sometimes called "single-trigger lite") combined with double-trigger on the remainder. The "single-trigger lite" gives the founder some value at close without removing all retention leverage.
• Distressed acquisitions: in fire-sale scenarios where the acquirer doesn't intend to retain executives anyway, single trigger may be acceptable because retention isn't the goal.
• Some executive packages at very-late-stage IPO-bound companies: pre-IPO, some executives negotiate single-trigger acceleration as a recruiting incentive when joining for IPO upside.

The negotiating reality at hiring: most modern offer letters propose double-trigger as the default. Single-trigger requires explicit negotiation and often requires senior leverage to obtain. The "single-trigger 25% + double-trigger remainder" structure is more negotiable than 100% single-trigger and is increasingly common at well-funded venture-backed companies for senior executives. What investors will resist: 100% single-trigger acceleration for anyone. Investors typically push for full double-trigger across the company and will negotiate hard at term-sheet stage to align with that structure.

What founders get wrong: Either (a) accepting double-trigger 100% without exploring single-trigger lite, leaving value on the table if the founder doesn't want to stay through transition, OR (b) pushing for full single-trigger 100% and getting nothing because investors and counsel resist. The right discipline: negotiate single-trigger lite (25-50% single, remainder double) as the realistic ask; document the change-of-control trigger definitions precisely; ensure the percentages and timing are clear in the equity grant agreement and Voting Agreement so they're enforceable at the actual transaction.

Related: Vesting Acceleration · Double Trigger Acceleration · Vesting · Acquisition · Founder Vesting

FAQ

What is single trigger acceleration?
A vesting acceleration structure where some or all of an equity holder's unvested shares vest immediately upon the occurrence of a single defined trigger event (typically change of control), without requiring any subsequent event such as termination. Removes the post-event retention lever.

Why is single trigger harder to negotiate than double trigger?
Because it removes the acquirer's retention lever (executives are fully vested at close and can leave freely), increases acquirer cost (need to grant new equity for retention), and misaligns incentives (executive incentive shifts to transaction completion rather than long-term value creation). Investors and acquirers resist single-trigger for these reasons.

What's "single-trigger lite"?
A common compromise structure where a portion of unvested shares (25-50%) accelerates on change of control alone and the remainder is subject to double-trigger acceleration. Gives the founder some value at close while preserving retention lever for the acquirer. More negotiable than 100% single-trigger and common in modern founder offer letters.