Cofounder vesting acceleration lets your unvested shares vest early when the company is sold. Single-trigger vests them at the sale. Double-trigger vests them only if you are also pushed out within a set window after it. Double-trigger is the market standard. What you negotiate is the percentage, the window, the definitions and what happens if the buyer cancels your grant.
If you have not set up the basic schedule yet, start with cofounder vesting schedules explained.
What is single-trigger vs double-trigger acceleration?
One event versus two. Single-trigger vests all your unvested shares when the company changes hands. Sign the deal and the equity is yours, whatever happens next (Cooley GO).
Double-trigger needs the sale plus a qualifying termination: you are fired without cause, or you resign for good reason, within a window after closing (Pulley). Keep your job after the deal and nothing accelerates. Get pushed out inside the window and your unvested shares vest at once.
Why does single-trigger rarely survive a deal?
Because it makes the company harder to sell. A buyer uses your unvested shares as the reason you stay through the integration. Single-trigger removes that reason, and buyers notice (Capbase). They lower the price, restructure the deal, or walk.
Double-trigger protects you from being dropped with nothing once the buyer no longer needs you, and still lets them keep the team through the transition (Cooley GO). That is why investors resist single-trigger and accept double-trigger.
What do you actually negotiate?
Three terms decide how much protection you have.
| Term | Typical range | What to push for |
|---|---|---|
| Percentage | 100% for founders and CEOs; 50% or 12 extra months for later hires (Pulley) | A specific number in writing |
| Window | 12 to 24 months after closing (The Startup Law Blog) | 18 to 24 months |
| Cause and good reason | Defined in the grant | Demotion, relocation and a much smaller role count as good reason |
The window matters more than it looks. A firing one day after a 12-month window closes gets nothing, even when it plainly comes from the deal. Buyers often restructure in waves, and the second wave tends to land 12 to 18 months after closing.
Vague definitions do the same damage. If "good reason" is loose, a buyer can shrink your job until you leave without ever firing you.
What if the buyer cancels your unvested shares?
Then double-trigger protects nothing. If the acquirer cancels, cashes out or swaps your unvested grant at closing, there is nothing left to accelerate later (Stock Option Counsel).
Add a separate clause: if your unvested shares would be cancelled without payment under the deal, they vest in full at closing. Without it, how the deal is structured can erase every term you negotiated.
When should cofounders agree acceleration terms?
Now, while you all still agree and no buyer is in the room. Terms first raised during an acquisition get settled fast and under pressure.
- Choose single or double trigger.
- Set the percentage for each founder.
- Set the window length.
- Define cause and good reason.
- Add the cancellation backstop.
- Put all of it in the grant documents, not only an offer letter a later deal can override.
The cofounder agreement checklist shows where these terms sit next to the rest of your agreement. To find which assumptions you two have never written down, take the free cofounder alignment check together. For a first draft, start from one of our founders agreement templates.
Frequently asked questions
- What is the difference between single-trigger and double-trigger acceleration?
- Single-trigger acceleration vests all unvested shares the moment one event happens, usually an acquisition. Double-trigger needs two events: the acquisition, then a firing without cause or a resignation for good reason within a set window, typically 12 to 24 months. Investors prefer double-trigger, and it is the market standard today.
- Why do investors push back on single-trigger acceleration?
- Buyers use unvested equity to keep a team in place after a deal. Single-trigger vests everything at closing, so that hold disappears. Acquirers lower their offer, change the deal structure or walk away from founders who insist on it, which means single-trigger can shrink the exit it was meant to protect.
- How much equity accelerates on a double trigger?
- There is no fixed rule. Founders and CEOs often negotiate 100 percent of unvested shares. Later hires and executives more often get 50 percent, or 12 extra months of vesting credited when they are let go. Because it is a straight negotiation, write a specific number into the documents rather than leaving it open.
- When should cofounders agree acceleration terms?
- When you write the founders agreement and grant documents, long before any buyer appears. Terms first negotiated during an acquisition are settled fast and under pressure. Deciding the trigger, the percentage, the window and the cancellation backstop while you still agree protects every founder before a deal exists.