See how much equity accelerates on M&A under your grant's acceleration provision.
Accelerated value
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Already vested
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Total payout
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What happens to your unvested equity in a buyout
When the company you work for gets acquired, the equity you have already earned is safe, but the unvested portion hangs on a single clause buried in your grant agreement: the acceleration provision. That clause decides whether your remaining shares vest immediately, vest only if you are also let go, or simply convert into the acquirer's stock with the original schedule intact. This calculator turns that legal language into a dollar figure by combining your total grant value, how much has vested, and which acceleration term you hold.
It is written for employees at startups facing a merger or acquisition, and for candidates negotiating an offer who want to understand what acceleration is worth before they sign. The vocabulary matters: single trigger means an event like the acquisition alone vests your shares, while double trigger requires two events, typically the acquisition plus losing your job afterward.
A $500,000 grant, 40 percent vested
Imagine a grant worth $500,000 of which 40 percent, or $200,000, has already vested, leaving $300,000 unvested. Under a double-trigger provision with full acceleration, all $300,000 of that unvested stock vests if you are terminated after the deal closes. Combined with what you already held, your total payout reaches $500,000. The same grant under a 50 percent double trigger would accelerate only $150,000, for a $350,000 payout, and a grant with no acceleration clause would pay just the $200,000 already vested while the rest converts to acquirer equity.
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The chart stacks the already-vested base against the accelerated portion for the double-trigger example.
Reading the result as risk, not as a paycheck
The number this tool produces is a what-if, and treating it as expected income is a common mistake. Under a double trigger, the accelerated value only materializes if two things both happen: a sale, and then your termination. In the far more common outcome where the company is not acquired, or is acquired and keeps you on, the unvested portion simply keeps vesting on its original schedule and no acceleration occurs. So the right mental model is insurance. The accelerated figure tells you how protected you are against the specific downside of being shown the door right after a deal, not how much money is coming your way. When you compare two job offers with different acceleration terms, you are really comparing how much severance-like cushion each one builds into a worst-case exit, which is genuinely valuable but easy to overvalue if you assume it always pays.
Why acquirers prefer double trigger
Single-trigger acceleration is rare for rank-and-file employees because it works against the buyer. An acquirer pays a premium partly to retain talent, and if everyone's equity vests the moment the deal closes, key people can cash out and walk. Double trigger aligns everyone: your unvested equity is protected if the new owner pushes you out, but you keep a reason to stay if they want you. The dollar value this tool shows is only realized in the bad scenario, a post-deal termination, which is exactly why it functions as insurance rather than a guaranteed windfall. One tax note the calculator does not model: a large accelerated payout lands as ordinary income in a single year and can spike your marginal rate, so a payout of this size warrants a conversation with a tax advisor.
Questions employees ask
How do I find out which acceleration I have?
Read your stock option agreement and the company's equity incentive plan, and look specifically for a change-of-control or change-in-control section. The terms are sometimes in the offer letter instead. If you cannot find clear language, assume you have none, since acceleration is the exception rather than the default.
Can the acquirer cancel my unvested options outright?
In some deals, yes, unvested options can be cashed out, assumed, substituted, or canceled depending on the merger agreement and your plan terms. Acceleration language is your protection against the harshest outcome, which is why negotiating at least double-trigger acceleration matters for senior hires.