Single vs. Double Trigger Acceleration: A Founder’s Guide

Single trigger: the company is sold, and all your remaining unvested equity vests immediately.

Double trigger: the company is sold, and you are then fired without cause within a specified period. All your remaining unvested equity vests when that second event occurs.

Those are the basic, full-acceleration versions. The comparison below uses those versions first, then explains how agreements can vary.

Single vs. Double Trigger: The Quick Comparison

What happens?	Single trigger	Double trigger
The company is sold and you keep your job	All remaining unvested equity vests at closing	You continue vesting on your existing schedule
The company is sold and you are then fired without cause within the agreed period	Your equity already vested at closing	All equity still unvested vests when you are fired
You are fired without a sale	No acceleration under this sale-based provision	No acceleration under this sale-based provision

The difference is simple: single trigger requires the sale; double trigger requires the sale plus a qualifying termination.

For double trigger, this comparison assumes the unvested equity and its acceleration protection continue after the acquisition. We cover what happens if they do not below.

What Is Single Trigger Acceleration?

In the basic sale-based version, single trigger means a sale of the company causes all your remaining unvested equity to vest immediately. You do not also have to lose your job. The sale is the one trigger.

If you stay with the buyer, the accelerated equity is already vested. If you leave afterward, you do not lose it merely because you have stopped working there.

This gives the founder or employee protection against selling the company before vesting is complete. The buyer, however, may need a new incentive to keep that person working after the sale. Pulley's explanation describes that retention tradeoff.

What Is Double Trigger Acceleration?

In the basic version, double trigger means all your remaining unvested equity vests only after both of these events occur:

1. The company is sold.
2. You are fired without cause within the period specified in your agreement.

If the company is sold and you keep working for the buyer, your equity continues vesting on its existing schedule. If the buyer then fires you without cause during the agreed period, whatever is still unvested vests immediately.

An agreement might use a 12-month period after closing, for example. That is an illustration, not a universal deadline. The agreement determines the actual period and may also cover resignation for defined good reason.

Double trigger preserves the incentive to stay while protecting someone who loses their role in connection with the sale. Orrick describes this balance.

Why Do Investors Prefer Double Trigger Acceleration?

Investors generally prefer double trigger in part because new employee retention packages can come at the expense of their sale proceeds. If key founders and employees become fully vested at closing, the buyer may need to offer new cash bonuses or equity to keep key people. The buyer can offset that additional cost by reducing the purchase price, leaving less for the selling shareholders, including investors. Cooley explains this concern directly.

Double trigger keeps the existing unvested equity working as an incentive to stay. That can reduce the need for replacement incentives while protecting founders and employees if they are later terminated without cause. As a16z explains, buyers consider the purchase price and retention packages as part of their total deal budget. Double trigger does not eliminate the need for new incentives, but it gives the buyer an existing retention tool to work with.

How Does This Work With Actual Shares?

Assume you have 1,000,000 shares. When the company is sold, 600,000 are vested and 400,000 are unvested.

• With full single trigger: The 400,000 unvested shares vest at closing. All 1,000,000 shares are now vested, whether you keep your job or not.
• With full double trigger: The sale alone does not accelerate the 400,000 shares. You keep vesting while you work for the buyer. If you are later fired without cause within the agreed period, all shares still unvested at that point vest immediately.

For example, if another 50,000 shares vest through continued service before that qualifying termination, the remaining 350,000 accelerate. All 1,000,000 shares are then vested.

These examples assume the shares or replacement interests continue after closing with the relevant protections. They illustrate vesting, not cash proceeds. Our startup acquisitions guide covers the wider transaction.

Does Full Vesting Mean I Get Paid for All My Equity?

Acceleration moves vesting forward. For restricted founder stock, that generally releases shares from the company's right to repurchase them at cost. For options, it generally makes the accelerated portion exercisable, subject to the plan, grant, and transaction terms. See founder vesting for the underlying mechanics.

Full vesting does not eliminate an option's exercise price or guarantee a payment. The deal's payout rules, the treatment of your equity, and taxes still determine what you receive. Carta's acquisition guide explains those separate questions.

Which Structures Favor the Company, Founder, or Employee?

These are practical tradeoffs, not fixed legal categories. A founder negotiating their own stock is the recipient. The same founder negotiating an executive's grant is acting for the company.

Structure	Protection for the recipient	Company, investor, and buyer tradeoff
No automatic acceleration right	No contractual promise of early vesting under this structure	Preserves flexibility, subject to the plan and transaction terms
Full single trigger on acquisition	All remaining unvested equity vests at the qualifying sale	May require replacement retention incentives that reduce the purchase price
Partial single trigger on acquisition	A defined portion vests at the qualifying sale	Provides an exit reward while leaving some equity subject to vesting
Single trigger on qualifying termination	Protection can apply without a sale	Increases the equity cost of removing or replacing the person
Double trigger	Protection if both the sale and qualifying termination occur	Preserves the existing retention incentive, which can help protect sale proceeds
Combined structure	A portion vests at closing; additional equity vests upon qualifying termination	Offers more protection at closing than double trigger alone

From the recipient's perspective, fewer conditions and more accelerated equity generally provide stronger protection. From the company's perspective, retention, recruiting, fairness to other holders, and transaction flexibility all matter.

Founders share the concern about sale proceeds too. When negotiating your own acceleration, weigh the protection you receive against the effect on the transaction as a whole.

What Other Acceleration Variations Should Founders Understand?

The simple definitions above describe full acceleration on a sale, or on a sale plus termination. Actual agreements can change the amount, triggering event, or conditions.

Termination without a sale

A qualifying termination can be the sole trigger, without any acquisition. The agreement might cover termination without cause, resignation for good reason, or both. This is another form of single trigger because one event is enough, but it is different from the sale-based version above.

That protects a founder or executive against losing unvested equity when removed from a role. It also makes personnel changes more expensive for the company. A company can have a legitimate reason to replace an ineffective executive without satisfying a narrow contractual definition of cause. Cooley's founder-stock guidance explains this concern.

Partial acceleration or additional vesting credit

The amount and trigger are separate choices. Either a single or double trigger can accelerate a portion rather than everything. Another approach gives the recipient credit for additional service, such as the shares that would vest over six more months.

Specify the calculation. "25% acceleration" could refer to the original grant or the remaining unvested balance. Those produce different results. Gunderson's founder-equity guide discusses additional months of service as one way to structure protection.

A combination of single and double trigger

An agreement can provide some acceleration at the sale and more upon a qualifying termination. For example, 25% of the remaining unvested equity might vest at closing, with full double trigger protection for the rest.

Using the 400,000 unvested shares above, that would mean 100,000 vest at closing. The other 300,000 continue vesting, with whatever remains unvested accelerating if the second trigger occurs. This is an illustrative negotiated structure, not an adoption statistic.

Acceleration if the buyer does not continue the award

A separate provision can require acceleration at closing if the buyer does not assume, continue, or replace the unvested award on the required terms.

This addresses a different risk from being fired after the acquisition. If the award disappears at closing, there may be nothing left for a later termination to accelerate. Cooley explains the assumption problem.

Ask how the protection carries into replacement stock, options, or a cash entitlement that remains subject to vesting. The documents should also state what happens if the required continuation does not occur. An SEC-filed executive agreement illustrates separate protection for non-assumption and qualifying termination. It is an example, not a startup benchmark.

Other specified events

Death or disability provisions can provide separate vesting protection. Performance milestones can also affect vesting, but a milestone-based schedule is not necessarily acceleration: it may simply define how the equity is earned from the outset.

For a founder reviewing acquisition protections, resolve the sale and termination mechanics first. Review any additional events separately rather than treating them as part of the same label.

Which Terms Make Acceleration More Protective or More Restrictive?

The following questions reveal more than "Do I have double trigger?"

1. What counts as a change in control? Check the transaction definition. Do not assume a financing, IPO, asset license, or hiring of the team qualifies.
2. How much accelerates? Identify the percentage, vesting credit, covered grants, and whether performance conditions also change.
3. What counts as cause? A broader definition can exclude more terminations from protection. Review the grounds, decision-maker, and any notice or opportunity to cure.
4. Does good reason apply? Defined reductions in duties or compensation, or required relocation, may allow a qualifying resignation. Disliking a new boss is not enough by itself.
5. What is the timing window? A longer post-closing window covers more potential terminations. A pre-closing window can address a removal shortly before the sale, if the agreement provides for it.
6. What procedures and conditions apply? Written notice, a cure period, a resignation deadline, or an effective release can determine eligibility even when the underlying event qualifies.
7. Does the protection survive the transaction? Identify what replaces the unvested equity and whether the same acceleration rights follow it.

Cooley's acceleration guide discusses good reason and pre-closing protection. The SEC-filed agreement cited above shows how notice, cure, resignation, and release requirements can operate together.

The recipient generally benefits from meaningful good reason protection, a usable window, and continuity of the award. The company needs objective definitions and workable procedures so routine business changes do not create unintended acceleration rights.

Should Founders and Employees Receive the Same Protection?

The analysis should account for role, equity size, recruiting needs, and the purpose of the grant. Founders, senior executives, and other employees do not necessarily receive identical terms. Gunderson's employee-equity guidance identifies acceleration as a term typically reserved for executives, key employees, and board members.

For your own founder equity, identify the loss you are trying to prevent. Acquisition-related job loss calls for a different discussion from removal before any sale.

For employee grants, decide whether protection belongs in a consistent policy or a specific recruiting package. Check the equity incentive plan, individual grant, employment terms, and approvals together. A promise in an offer letter should match the operative equity documents.

In either case, ask counsel to walk through three scenarios: a sale with continued employment, a sale with qualifying termination, and termination without a sale. Then ask what changes if the buyer does not continue the award.

Frequently Asked Questions

Does single trigger always mean all my equity vests at acquisition?

In the basic sale-based version with full acceleration, yes: all remaining unvested equity vests at closing. But an agreement can provide partial acceleration or use a different event as the single trigger, so check the actual terms.

Does double trigger protect me if I am fired before any acquisition?

Usually not on its own. Both events must satisfy the agreement. A pre-closing window can cover a termination before a later qualifying sale, but protection for termination without any sale needs a separate provision.

Can I resign after an acquisition and receive acceleration?

Only if the agreement covers the resignation and you satisfy its conditions. Good reason is a defined contractual standard, often with notice, cure, and resignation deadlines.

What if the buyer cancels my unvested options at closing?

A later termination may have nothing left to accelerate. Review the plan, grant, and acquisition documents for continuation of the award or separate protection if it is not continued.

Is double trigger acceleration the same as double trigger RSUs?

No. Double trigger RSUs generally combine a service condition with a liquidity or other specified event. Double trigger acceleration concerns early vesting after a transaction and qualifying termination. Carta distinguishes these concepts.

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This post is for general informational purposes only and does not constitute legal or tax advice. Equity rights depend on the governing documents, transaction terms, applicable law, and specific facts. Consult qualified legal and tax advisors about your situation.

Want to understand what your equity documents protect? Book a free call to discuss your vesting and acceleration terms.