What Happens to Stock Options When a Company Is Acquired: Acceleration, Assumption, and Cash-Out

What Happens to Stock Options When a Company Is Acquired? 2026 Employee Guide

What happens to stock options when a company is acquired depends on four levers written into your equity plan and the deal documents: whether your options are vested or unvested, whether the buyer pays cash or stock, whether your grant has single-trigger or double-trigger acceleration, and whether your option is an Incentive Stock Option (ISO), a Non-Qualified Stock Option (NSO), or a Restricted Stock Unit (RSU). The four possible outcomes are cash-out at the deal price, assumption and conversion into the acquirer’s equity, accelerated vesting, or outright cancellation of unvested awards. Most deals combine two or three of these treatments and apply different rules to vested versus unvested grants.

This guide covers the mechanics for ISOs, NSOs, and RSUs, the tax treatment under Internal Revenue Code (IRC) Section 422, 424, 83, and 409A, the Section 280G golden parachute cutback rules for executives, and a decision framework you can run against your own grant before close. Real acquisitions referenced include Microsoft-Activision, Musk-Twitter, Salesforce-Tableau, and Adobe-Figma.

TL;DR: The Four Acquisition Outcomes for Stock Options

If you have ten minutes, this table covers most of what you need. Each subsequent section drills into mechanics and tax.

Outcome	What Happens to Vested	What Happens to Unvested	Tax Trigger	Frequency
Cash-Out	Exercised and sold at deal price; net spread paid in cash	Forfeited, accelerated, or cashed out depending on plan	Ordinary income (NSO) or disqualifying disposition (ISO)	Roughly 60% of deals per Carta acquisition data
Assumption + Conversion	Converted to acquirer options at exchange ratio	Converted and continues vesting on original schedule	No event at close if Section 424 conditions met	Common in stock-for-stock deals, roughly 25%
Acceleration	Already vested; may also be cashed out	Vests early on single-trigger or post-termination on double-trigger	Ordinary income (NSO) or Alternative Minimum Tax (AMT) preference (ISO)	Single-trigger 10%, double-trigger 70% of plans per Equilar
Cancellation	Rare for vested; usually paid out	Forfeited with no payment	Generally no immediate tax	Most common when buyer does not retain employees

Almost every deal mixes these. Vested options often cash out while unvested options are assumed. Executive grants may carry single-trigger acceleration that rank-and-file grants do not. The starting point for any employee is to read the grant agreement, the equity incentive plan document, and the merger agreement section labeled “Treatment of Stock Options” or “Treatment of Equity Awards.”

Outcome 1: Cash-Out at the Deal Price

Cash-out is the simplest and most common outcome. The acquirer pays a per-share price, your vested options are deemed exercised at that price, and you receive the spread (deal price minus your strike price) multiplied by your vested share count. The cash typically lands within 30 to 90 days of close, sometimes through an escrow agent who also administers shareholder consideration.

Here is a worked example. You hold 10,000 vested NSOs at a $2.00 strike. The buyer pays $15.00 per share in cash. Your gross spread is ($15.00 minus $2.00) times 10,000, or $130,000. The company withholds federal income tax at the supplemental rate of 22% on amounts up to $1 million and 37% above, plus Social Security up to the 2026 Social Security wage base of $176,100, Medicare at 1.45%, the Additional Medicare Tax of 0.9% above $200,000, and any state income tax. You receive roughly $80,000 to $90,000 net depending on state. IRS Publication 525 covers the supplemental wage treatment.

For ISOs, cash-out within one year of exercise or two years of grant creates a disqualifying disposition under IRC Section 422(a)(1). The spread between strike and fair market value at exercise is reported as ordinary W-2 wages, and any further appreciation between exercise and sale is short-term or long-term capital gain depending on holding period. The favorable ISO treatment of long-term capital gains on the entire spread requires holding past both the one-year-from-exercise and two-year-from-grant thresholds, which a cash-out generally prevents.

Cash-out treatment of unvested options varies. Some plans accelerate and cash out at close, some convert to deferred cash vesting on the original schedule, and some cancel outright. The Harvard Law School Forum on Corporate Governance deal-document studies show roughly a third of cash deals fully accelerate, a third use deferred cash, and a third cancel unvested awards.

Per Carta’s analysis of more than 1,000 acquisitions, cash-out is the dominant treatment for vested options. It is administratively simple, removes the buyer’s obligation to maintain a legacy plan, and gives employees liquidity at the negotiated price.

Outcome 2: Assumption and Conversion into Acquirer Equity

In a stock-for-stock acquisition, the buyer often assumes the target’s outstanding stock options and converts them into options to purchase the buyer’s stock. The mechanic is an exchange ratio applied to both the strike price and the share count, so the in-the-money spread before and after the conversion is the same.

The formulas are:

New shares = Old shares times exchange ratio
New strike = Old strike divided by exchange ratio
Vesting schedule rolls forward unchanged

Worked example. You hold 5,000 vested NSOs at a $4.00 strike in TargetCo. AcquirerCo buys TargetCo at an exchange ratio of 0.50 AcquirerCo shares per TargetCo share. After conversion, you hold options on 2,500 AcquirerCo shares with a strike of $8.00. If AcquirerCo trades at $30.00 post-close, your spread is ($30.00 minus $8.00) times 2,500, or $55,000, identical to what you held in TargetCo at the implied $15.00 per share deal price.

For ISOs, IRC Section 424(a) and the corresponding Treasury regulations at 26 CFR Section 1.424-1 allow assumption without triggering a disqualifying disposition, as long as three conditions are met. First, the spread immediately after the substitution cannot exceed the spread immediately before. Second, the ratio of strike to fair market value cannot decrease. Third, the new option cannot give the holder additional benefits. When these conditions are met, the original grant date, the one-year-from-exercise clock, and the two-year-from-grant clock all carry forward.

For NSOs, the parallel rules under IRC Section 409A and Treasury Regulation Section 1.409A-1(b)(5)(v)(D) require that the assumed option carry the same spread and ratio. Failure to meet these conditions can convert the assumption into a Section 409A violation, triggering immediate income inclusion, a 20% additional tax, and an interest penalty. Buyers retain specialist tax counsel precisely to avoid this outcome.

Vesting schedules typically roll forward unchanged. If you were 50% vested at close with two years remaining, you remain 50% vested in the new options and continue vesting on the same monthly or quarterly cadence. Some plans accelerate a portion at close (single-trigger) or upon involuntary termination (double-trigger), discussed in the next section.

Assumption is common in stock-for-stock deals such as the 2019 Salesforce acquisition of Tableau, the 2022 Microsoft acquisition of Nuance Communications, and the proposed but ultimately abandoned 2022-2023 Adobe acquisition of Figma. The 2019 Salesforce-Tableau press release and proxy materials disclose the conversion mechanics including the 1.103 exchange ratio that converted Tableau options into Salesforce options.

Outcome 3: Acceleration (Single-Trigger vs Double-Trigger)

Acceleration means unvested options vest earlier than the original schedule because of the acquisition. Two flavors exist, and the difference matters enormously to employees who are not founders or senior executives.

Single-trigger acceleration vests unvested options at the acquisition closing. The triggering event is the acquisition itself. No additional condition (like termination) is required. Single-trigger is common for founders, sometimes for C-suite executives, and rare for rank-and-file employees. Per Equilar’s executive compensation studies, roughly 10% of broad-based equity plans carry single-trigger acceleration for the average employee.

Double-trigger acceleration requires two events. The first trigger is the acquisition. The second trigger is involuntary termination without cause, or constructive termination through a material reduction in role or compensation, within a protected window after closing. The window is typically 12 to 18 months. If both triggers occur, unvested options vest. If only the first trigger occurs (acquisition without termination), the employee continues vesting under the acquirer with no acceleration. Per SHRM’s equity compensation surveys, double-trigger is the standard structure in roughly 70% of broad-based plans.

Feature	Single-Trigger	Double-Trigger
Vesting accelerates when?	At acquisition close	At involuntary termination within 12 to 18 months post-close
Employee retention incentive	Weak (already vested)	Strong (must stay or get terminated)
Frequency for rank-and-file	Roughly 10%	Roughly 70%
Frequency for founders	Common	Sometimes layered on top
280G parachute risk	Higher	Lower if termination is unrelated to deal value

Tax treatment on acceleration. For NSOs, acceleration creates ordinary income at exercise equal to the spread between strike and fair market value at the acceleration date, reported on a W-2 with supplemental withholding. For ISOs, acceleration itself is not a taxable event, but exercising the accelerated options creates an AMT preference item under IRC Section 55 equal to the spread between strike and fair market value at exercise. The AMT preference can drive a substantial parallel tax liability in the acceleration year, and employees should model the AMT impact before exercising. IRS Form 6251 is the worksheet.

For executives, single-trigger acceleration interacts with IRC Section 280G’s golden parachute rules. If the present value of all acquisition-related compensation (including accelerated equity, retention bonuses, and severance) equals or exceeds three times the executive’s average annual W-2 wages for the prior five years, the excess over one times the base amount is non-deductible to the company and subject to a 20% excise tax on the recipient under IRC Section 4999. Most equity plans contain a 280G cutback provision that reduces parachute payments to the safe harbor amount, or a best-after-tax provision that pays in full but pushes the 4999 tax to the executive. Cleary Gottlieb and Wachtell client alerts on 280G survey deal practice on these provisions.

Outcome 4: Cancellation Without Payment

Cancellation is the worst outcome for the employee. Unvested options are forfeited at close and the employee receives nothing for them. This treatment is most common when the buyer does not want to retain target’s employees, when the deal is at or below the strike price (options are underwater), or when the buyer plans to issue new acquirer-level grants in place of legacy target grants.

Cancellation rarely applies to vested in-the-money options, which are almost always cashed out or assumed because they represent a contractual right the buyer must address. Vested out-of-the-money options may be canceled, though some deals pay a nominal consideration to clean up the cap table. Unvested options are the typical cancellation target. Per deal-document studies from Harvard Law School Forum on Corporate Governance, unvested cancellation appears in roughly 20% of acquisitions, concentrated where the target’s workforce is largely redundant with the buyer’s existing staff.

Cancellation often comes paired with retention bonuses: typically 50% to 150% of base salary, vesting 6 to 24 months post-close, in exchange for accepting the cancellation and committing to stay. The bonus is taxable as ordinary income at vest.

Tax consequence of cancellation: forfeiture of an unvested option is generally not a taxable event because the employee had no vested property right. No income is recognized and no deduction is available. The economic loss is real but produces no tax benefit. For employees who early-exercised unvested options under a reverse-vesting structure and later forfeit, the basis paid is generally returned, with any loss treated under AICPA-published early-exercise unwind guidance.

ISO-Specific Considerations in an Acquisition

Incentive Stock Options carry favorable tax treatment if specific holding rules are met, and acquisitions stress those rules in particular ways. IRC Section 422 sets the qualifying conditions, IRC Section 424 governs substitution and assumption in M&A, and the regulations at 26 CFR Sections 1.422-1 through 1.422-5 fill in operational detail.

First, the 90-day post-termination exercise window. IRC Section 422(a)(2) requires that an ISO be exercised within three months of termination of employment to retain ISO treatment. The 90-day window is NOT extended for M&A absent specific plan language. If an acquisition triggers your termination and you have unexercised vested ISOs, the clock starts running. Exercise within 90 days or the options either expire (under the plan) or convert to NSO treatment for tax purposes.

Second, the $100,000 annual vesting limitation. IRC Section 422(d) caps the aggregate fair market value (at grant) of ISO stock first becoming exercisable in any calendar year at $100,000 per employee. Acceleration in connection with an acquisition can push a large block of unvested ISOs over this threshold in a single year. The excess above $100,000 is automatically treated as NSO for tax purposes. The IRS treats the excess as NSO from the bottom up by grant date, meaning earlier grants exhaust the $100,000 limit first. Publication 525 and the regulations cover the ordering.

Third, AMT impact on acceleration. Exercise of an ISO creates a preference item under IRC Section 55 equal to the spread between strike and fair market value at exercise. The preference is added back to regular taxable income for AMT purposes. In an acquisition year, accelerated ISO exercise can drive a six- or seven-figure AMT liability that survives even if you never sell the shares. The National Center for Employee Ownership publishes worked AMT examples for ISO acceleration scenarios.

Fourth, long-term capital gain holding period reset on cash-out. Cash-out within one year of exercise or two years of grant creates a disqualifying disposition. The spread at exercise becomes ordinary W-2 wages, and any additional gain above the exercise price is short-term or long-term capital gain depending on the disposition timing. Employees who exercised ISOs in the months leading up to an acquisition close should model the cash-out tax carefully. A planned cash-out can convert what would have been long-term capital gain into ordinary wages.

Fifth, Section 424 continuity. Assumption or substitution under IRC Section 424(a) preserves ISO status if three conditions are met: the post-substitution spread does not exceed the pre-substitution spread, the post-substitution ratio of strike to fair market value is not less than the pre-substitution ratio, and the substituted option does not give the optionee additional benefits. 26 CFR Section 1.424-1 walks through the math. When the conditions are met, the original grant date and holding period clocks survive the deal.

NSO-Specific Considerations in an Acquisition

Non-Qualified Stock Options are taxed under IRC Section 83 at exercise (or vesting if reverse-vested early exercise was elected under Section 83(b)). The basic rule is that the spread between strike and fair market value at exercise is ordinary W-2 income, subject to federal income tax withholding at supplemental rates, Social Security up to the wage base, Medicare, the Additional Medicare Tax above $200,000, and any state income tax.

In an acquisition, NSO treatment is more flexible than ISO. The buyer has more room to modify the option without triggering adverse tax consequences, because no equivalent of the Section 422 qualifying conditions applies. The main constraint is IRC Section 409A. If the buyer modifies the option in a way that lowers the strike below the fair market value at modification, the option becomes deferred compensation subject to Section 409A, and the holder faces immediate income inclusion of the in-the-money spread, a 20% additional tax, and an interest charge. Treasury Regulation Section 1.409A-1(b)(5)(v)(D) provides a safe harbor for option assumptions that maintain the pre-modification spread and ratio.

Cash-out of vested NSOs at acquisition close creates ordinary W-2 income equal to the deal price minus strike, multiplied by shares. The employer withholds at the supplemental rate of 22% (37% above the $1 million threshold) for federal income tax, plus Social Security up to the wage base, Medicare, the Additional Medicare Tax, and state withholding. Net cash to the employee is typically 55% to 70% of the gross spread depending on state and total wage level. IRS Publication 15 covers supplemental withholding mechanics.

Acceleration of unvested NSOs creates a similar ordinary income event at the acceleration date. If the unvested NSOs are accelerated and cashed out, the employee recognizes ordinary income equal to deal price minus strike. If the unvested NSOs are accelerated and assumed (rolled into acquirer equity), no immediate tax event occurs as long as the Section 409A safe harbor is met.

Section 409A is the key risk area in NSO acquisitions. Modifications, extensions, and accelerations all carry 409A risk if the strike is below fair market value at modification or if the modification introduces new deferral features. The classic trap is a buyer that extends the post-termination exercise window beyond the original term, which can be treated as a new option grant at a discount under Treasury Regulation Section 1.409A-1(b)(5). Specialist tax counsel typically reviews any NSO modification language in the merger agreement.

RSU Treatment in an Acquisition

Restricted Stock Units differ from options in a fundamental way. An option gives the holder the right to buy stock at a strike price. An RSU gives the holder the right to receive stock (or its cash value) at vesting, with no exercise price. The acquisition mechanics differ accordingly.

Many private-company RSUs carry double-trigger vesting where the two triggers are (a) the time-based vesting schedule and (b) a liquidity event such as an IPO or acquisition. Until both triggers are met, the RSU is unvested and unfunded. In an acquisition, the liquidity-event trigger fires at close. Time-vested RSUs convert to vested stock or cash. Unvested RSUs (the time component not yet satisfied) accelerate, continue under the acquirer, or are forfeited depending on the plan and the merger agreement.

Equity Type	Tax at Acquisition	Vesting Acceleration Norm	Most Common Outcome
ISO	Ordinary income on disqualifying disposition, AMT preference on exercise	Plan-dependent, double-trigger most common	Cash-out with disqualifying disposition
NSO	Ordinary W-2 income at exercise or cash-out	Plan-dependent, double-trigger most common	Cash-out or assumption
RSU (single-trigger time)	Ordinary income at vest	Often accelerates on acquisition	Cash-out at deal price
RSU (double-trigger)	Ordinary income at second trigger	Liquidity trigger fires at close	Conversion to vested stock or cash

Tax on RSU acquisition. Vesting of an RSU creates ordinary income equal to the fair market value of the underlying stock at vest, reported on the W-2. In an acquisition, the deal price serves as fair market value if the RSU is cashed out. If the RSU rolls into acquirer stock, the acquirer’s share price at the substitution date sets the income amount. The employer has a mandatory withholding obligation equal to supplemental federal income tax, Social Security, Medicare, and state tax. For cash-settled RSUs, the employer simply withholds from the cash payment. For stock-settled RSUs, the standard mechanism is “sell-to-cover,” where the employer sells a portion of the vesting shares on the open market (or to the company itself) to fund the withholding.

The mandatory withholding is the operational difference between RSUs and options. Option holders choose when to exercise and can plan the tax year; RSU holders cannot. In an acquisition year, RSU vesting can interact with other income (option cash-out, retention bonuses, severance) to push the employee into a higher marginal bracket, the Additional Medicare Tax threshold, and the net investment income tax under IRC Section 1411.

Severance and Retention Bonus Alternatives

Acquirers often pair option treatment with cash retention and severance packages. The economics replace some of the foregone equity value with cash that depends on continued employment or involuntary termination.

Retention bonuses are cash payments conditioned on continued employment for a defined period post-close. Typical structures range from 50% to 150% of annual base salary, vesting in 6 to 24 months post-close, paid in lump sums at milestone dates or as the period elapses. The bonus replaces the foregone upside on unvested options that are canceled at close. Per WTW (Willis Towers Watson) M&A retention surveys, roughly 70% of acquisitions include retention bonus programs for at least selected employees, and the average key-employee retention pool is 1% to 2% of deal value.

Severance packages cover involuntary termination without cause within a protected window post-close. Typical structures range from 3 to 12 months of base salary plus continued health benefits under COBRA for 6 to 18 months. Severance is W-2 income with supplemental withholding and counts toward the Section 280G parachute threshold for executives.

Trade-offs to weigh. A retention bonus paid in cash 12 months post-close is worth more, in expected-value terms, than unvested options whose future value depends on the acquirer’s stock performance. The retention bonus is taxable as ordinary income at vest, while option gains can sometimes qualify for long-term capital gains treatment (ISOs with proper holding) or qualified small business stock exclusion under IRC Section 1202. Cash is more certain, equity has higher upside variance. The optimal package depends on personal risk tolerance, tax bracket, the acquirer’s stock outlook, and the employee’s confidence in continued employment.

Tax Planning at Acquisition

Acquisition years concentrate large amounts of income into a single tax year. Planning before the year ends is the single most valuable move an employee can make.

AMT timing for ISO exercises. If you exercise ISOs in the acquisition year, the spread between strike and fair market value at exercise is an AMT preference item. The AMT liability can be substantial. Exercising in tranches across two tax years can reduce the AMT bite, but acquisition timing usually forecloses this option. Modeling the AMT before exercise is essential. Form 6251 is the worksheet, and a tax projection software or a CPA running parallel regular-tax and AMT calculations is the right tool.

10b5-1 plans for post-close selling. If the acquirer’s stock is publicly traded and you receive acquirer shares (through assumption or RSU conversion), establishing a Rule 10b5-1 trading plan before you have material non-public information is a defensive measure against insider trading liability and gives a structured way to diversify. The SEC’s 2022 amendments to Rule 10b5-1 imposed a 90- to 120-day cooling-off period between plan adoption and the first trade. Plan early in the post-close period.

Wash-sale rules. If you sell acquirer shares at a loss after a cash-out and repurchase substantially identical shares within 30 days before or after the loss sale, IRC Section 1091 disallows the loss. The disallowed loss adds to the basis of the replacement shares. Acquisition years where stock prices move sharply can trigger wash-sale traps that careful planning avoids.

QSBS Section 1202 continuity. If your target shares qualify for Section 1202 qualified small business stock exclusion, the acquisition may or may not preserve the 5-year holding period. A stock-for-stock acquisition where the acquirer is also a QSBS-qualified C corporation can sometimes preserve QSBS status under IRC Section 1202(h)‘s tacking rules. A cash acquisition terminates QSBS status. Tax counsel review of QSBS continuity is essential when the underlying shares represent a substantial gain.

State tax considerations. California, New York, Massachusetts, and other high-tax states tax option income based on the source of the work performed during the vesting period. An employee who worked in California during the vesting period but moved to Nevada before exercise still owes California tax on the California-source portion of the income. California FTB Publication 1004 covers the multistate sourcing rules for equity compensation.

Recent Acquisitions and How Options Were Treated

Recent deals illustrate the patterns above. Each acquisition’s proxy statement and merger agreement disclose the option treatment in detail.

Acquisition	Year	Deal Type	Option Treatment	Source
Microsoft / Activision Blizzard	Closed October 2023	$95.00 per share cash	All vested options cashed out at $95 minus strike; unvested RSUs converted to Microsoft RSUs on equivalent value basis	Activision DEFM14A
Elon Musk / Twitter	Closed October 2022	$54.20 per share cash	All vested options cashed out at $54.20 minus strike; unvested RSUs accelerated and cashed out; controversy on the $7.2 million Parag Agrawal payout	Twitter DEFM14A
Salesforce / Tableau	Closed August 2019	Stock-for-stock at 1.103 ratio	All Tableau options assumed by Salesforce and converted at 1.103 exchange ratio; vesting schedule rolled forward	Salesforce S-4
Adobe / Figma (abandoned)	Terminated December 2023	Hybrid cash and stock	Would have assumed Figma options with hybrid cash + Adobe stock conversion; terminated due to regulatory challenges	Adobe and Figma joint statement December 2023
Cisco / Splunk	Closed March 2024	$157.00 per share cash	All Splunk options cashed out; unvested RSUs converted to Cisco RSUs with continued vesting	Splunk DEFM14A

Microsoft and Activision closed in October 2023 after a long regulatory fight in the United States, United Kingdom, and European Union. The merger agreement provided 100% cash consideration at $95.00 per share, with vested options cashed out and unvested RSUs converted to Microsoft RSUs determined by dividing the per-share consideration by the volume-weighted average price of Microsoft stock over a defined measurement period.

Twitter and Elon Musk closed in October 2022 at $54.20 per share cash. All vested options were cashed out. Unvested RSUs accelerated and were cashed out. Senior executive change-of-control packages drew media attention, particularly the roughly $7.2 million package paid to outgoing CEO Parag Agrawal disclosed in the Twitter proxy. Wall Street Journal coverage and Bloomberg reporting covered the parachute details.

Salesforce-Tableau in 2019 illustrates stock-for-stock assumption. The 1.103 exchange ratio applied to all outstanding Tableau options. Vesting schedules continued unchanged under Salesforce. ISO continuity under Section 424 was preserved because the spread and ratio conditions were met.

Decision Framework for Employees

If you have stock options in a company that is being acquired (or that you think might be acquired), run through this decision framework.

Step	If Cash-Out Deal	If Assumption Deal	If Acceleration Triggers
1. Read the documents	Merger agreement Section on equity treatment + grant agreement	Merger agreement + grant agreement + acquirer’s equity plan	Equity plan acceleration provisions + employment agreement
2. Calculate gross value	(Deal price minus strike) times vested shares	Exchange ratio applied to strike and shares; net spread unchanged at close	Strike and FMV at acceleration date; AMT preference if ISO
3. Model the tax	Supplemental withholding + AMT for ISO + state tax	No immediate tax if Section 424 or 409A safe harbor met	Ordinary income at vest (NSO) or AMT preference (ISO)
4. Time your exercises	Consider early exercise to start LTCG clock if pre-close	Review acquirer’s vesting schedule for changes	Model multi-year exercise to spread AMT
5. Talk to a tax advisor	Mandatory above $100,000 option value	Mandatory if QSBS continuity is at stake	Mandatory if 280G parachute risk for executives

Three expensive mistakes employees commonly make. First, failing to read the equity plan acceleration provisions before signing on. Single-trigger acceleration in a founder grant is worth real money in an acquisition. Plans without acceleration leave employees exposed to cancellation. Second, failing to plan ISO exercises around AMT. Acceleration of a large block of ISOs in a single year can produce an AMT bill that exceeds the cash available from the exercise. Third, failing to address state tax sourcing. California in particular taxes option income based on work performed during the vesting period, and employees who moved out before an acquisition still owe California tax on the pre-move portion.

Always talk to a tax advisor when option value crosses $100,000 of expected acquisition consideration. The advisor’s fee is small relative to the AMT, state-sourcing, and 409A exposures at risk.

What to Read in the Merger Agreement

The merger agreement is the controlling document for option treatment. Find the section labeled “Treatment of Stock Options,” “Treatment of Equity Awards,” or “Company Equity Awards.” It is typically in Article I or II and runs two to five pages. Key items to identify: the definition of vested versus unvested at closing, the per-share consideration formula, treatment of unvested options, timing of cash payment, withholding mechanics, acceleration triggers, treatment of underwater options, and treatment of options held by non-employee directors and consultants.

The merger agreement is filed with the SEC for public-company targets as an exhibit to the DEFM14A proxy or Form 8-K. EDGAR hosts the filings. For private-company targets, the merger agreement is not public, but employees should be entitled to receive it as part of the option-cancellation or option-conversion notice required by their plan.

Frequently Asked Questions

Do I get to exercise my unvested options when my company is acquired? Only if your plan has single-trigger acceleration. Most plans use double-trigger, meaning your unvested options accelerate only if you are involuntarily terminated within a protected window (typically 12 to 18 months) after close. Roughly 70% of broad-based plans are double-trigger, 10% are single-trigger, and the remainder have no acceleration.

What happens to underwater options (strike above deal price)? Most acquirers cancel underwater options without payment because they have no economic value. Some plans require a nominal payment (often $0.01 per share) to clean up the cap table.

How quickly do I get my cash after the deal closes? Typical timing is 30 to 90 days after close. The cash flows from the acquirer to a paying agent who pays option holders after they execute an option surrender form. Some deals hold 5% to 15% of consideration in escrow for 12 to 24 months to back representations and warranties.

Will I owe AMT on an ISO acceleration? Possibly. Exercise of an ISO creates an AMT preference equal to the spread at exercise. If the preference exceeds your AMT exemption (roughly $87,000 single and $135,000 married filing jointly for 2026, with phaseouts), you will owe AMT. The liability can survive even if the shares lose value before you sell. Model the AMT before exercise using Form 6251.

What happens to my 90-day post-termination exercise window if the acquirer keeps me on? The 90-day window only starts running if employment terminates. Continued employment with the acquirer (after assumption) does not start the clock. At that point you have 90 days to exercise vested ISOs for ISO tax treatment.

Internal Resources for Further Reading

Related guides covering adjacent topics:

TL;DR and Seven Takeaways

Stock options in an acquisition resolve through four outcomes: cash-out, assumption and conversion, acceleration, or cancellation. Most deals mix two or three of these treatments and apply different rules to vested versus unvested grants.

Seven takeaways:

Read your grant agreement and equity plan. Single-trigger versus double-trigger acceleration is the single most important factor for unvested options.
Vested in-the-money options almost always cash out or assume. Cancellation of vested options is rare.
Unvested options face four possible fates: accelerate, assume, cash out, or cancel. Plan language and merger-agreement language control.
ISOs carry favorable tax treatment but create AMT exposure on exercise. The 90-day post-termination exercise window is not extended for M&A absent specific plan language.
NSOs create ordinary income at exercise. Section 409A is the key trap on buyer modifications.
RSUs vest at the liquidity-event trigger in most private-company plans. Mandatory withholding through sell-to-cover is the operational difference from options.
Talk to a tax advisor when option value crosses $100,000 of expected acquisition consideration. AMT, state-sourcing, 280G, and QSBS continuity are all six- and seven-figure exposures that planning can mitigate.

The merger agreement is the controlling document. The equity plan and grant agreement set the baseline. Your offer letter, employment agreement, and any change-of-control agreement layer additional protections on top. Together they tell you what happens to your stock options when your company is acquired.