Should I Sell Stock After an Acquisition?

By Kevin Luu, Co-Founder and Chief Learning Officer. Reviewed on 2026-09-30.

Should you sell stock after an acquisition? If the deal paid cash, there is nothing left to decide: your shares were sold at closing and the gain is taxable that year. If you received the buyer’s stock, the merger did not make the decision for you. Ask the same question you would ask of any holding: would you buy this many shares of the buyer today with cash? If the honest answer is no, the usual next step is to sell down to a size you would choose, and use the tax rules to decide how and when.

For an employee of the acquired company, the answer usually leans toward selling more than an outside investor would. Your salary, your unvested awards and now your shares all depend on one company. This article covers that sell-or-hold decision. For the mechanics of what happens to each type of share and award at closing, see If a Company Sells, What Happens to My Stock?

Three deal types, three different starting points

• All-cash deal. Every share converts into the deal price at closing. That is a sale for tax purposes. The only choice you had was whether to sell earlier on the market, which can move the gain into a different tax year.
• All-stock deal. In a deal that qualifies as a tax-free reorganization under IRC Section 368, you receive buyer shares with no tax at closing. Your old cost basis and holding period carry over to the new shares. The buyer’s Form 8937 shows how to allocate basis.
• Cash and stock. The cash portion (often called “boot”) is generally taxable up to your gain on the exchange, under IRC Section 356. The buyer shares keep your holding period, and their basis is your old basis reduced by the cash received and increased by any gain recognized.

The rest of this article is about the second and third cases: you now hold buyer stock and have to decide what to do with it.

Between announcement and closing: sell now or wait for the deal price?

After a deal is announced, the target’s stock usually trades a little below the offer price. That gap is the market’s price for the risk that the deal is blocked by regulators, voted down or renegotiated. Waiting until closing earns the gap if the deal goes through. Selling now gives up the gap and removes the risk that the stock falls back toward its pre-announcement price if the deal fails.

For most families the gap is small next to the downside of a broken deal. Two practical points matter more:

• Trading restrictions. Many employees of the target are blocked from trading during parts of the deal process under the company’s insider trading policy. Check with your legal or stock plan team before placing any order.
• Tax year. If closing is expected in early January, selling in December puts the gain in the current year. Waiting defers it. Which is better depends on what else is landing in each year, such as a large RSU vest or a sign-on payment from the buyer.

After closing: the test for buyer shares

A tax-free exchange defers the tax. It does not remove the risk. A common pattern after a merger is a family that keeps every buyer share because selling “costs” tax, while the same family would never have spent that much cash to buy the stock. Three questions sort this out:

1. What share of your liquid net worth is now in the buyer? Count shares you own plus unvested buyer RSUs at today’s price. There is no official limit for concentration. Your own number depends on your other assets, your job security and how much of your income already comes from the same company.
2. What is the after-tax cost of selling? Work out the actual dollars, by lot, in your state. It is often smaller than people assume, especially for long-term lots.
3. What would a fall in the buyer’s price cost you? Compare a plausible drop (the example below uses an illustrative 30%) with the tax bill. If a 30% fall costs more than the tax, the tax is a weak reason to hold.

Worked example: a $1.1 million California household in a stock deal

Assumptions (illustrative): married filing jointly, $1,100,000 of W-2 income in 2026, modest deductions so California taxable income is above $1,000,000 before the deal. One spouse works at a biotech that is acquired in an all-stock deal at 0.6 buyer shares per share. They own 3,000 target shares from vested RSUs and ESPP with a total basis of $240,000, all held more than one year and past any ESPP qualifying holding period. The buyer trades at $300. They also receive $400,000 of unvested buyer RSUs in exchange for their unvested awards.

At closing they own 1,800 buyer shares worth $540,000, with the same $240,000 basis carried over. No tax is due at closing. Their liquid assets outside the buyer are $1,200,000. Counting the unvested RSUs, $940,000 of their $2,140,000 of liquid and near-liquid wealth (about 44%) now depends on the buyer, on top of a paycheck.

How the 36.1% is built for this household in 2026: long-term gains above $613,700 of federal taxable income are taxed at 20% (Rev. Proc. 2025-32), plus the 3.8% Net Investment Income Tax, plus California’s 11.3% bracket and the 1% Behavioral Health Services Tax on taxable income over $1,000,000 (12.3% combined, using the latest published 2025 California brackets, where 11.3% runs from $891,542 to $1,485,906 for joint filers). California has no lower rate for capital gains. So: $300,000 x (20% + 3.8% + 12.3%) = $108,300.

The point of the table: holding avoids a $108,300 tax bill today but leaves $540,000 exposed to a single stock. A 30% decline would cost $162,000, which is more than the tax. In California, splitting the sale across two years does not change the rate much for a household at this income. It only spreads the cash flow.

The same family in Washington

Washington has no tax on wages in 2026, but it does tax long-term capital gains: 7% on gains above the annual standard deduction, and 9.9% on taxable gains above $1,000,000 (WA DOR). The latest published standard deduction is $278,000 for 2025, per married couple (WA DOR capital gains tax). Assuming no other long-term gains that year, selling all the shares in one year would add about $1,540 of Washington tax ($300,000 minus $278,000, times 7%), on top of the $71,400 federal tax ($300,000 x 23.8%). Splitting the sale so each year’s gain is $150,000 could bring the Washington tax to zero, if the 2027 deduction stays at a similar level. Here, timing matters more than it does in California.

One caution for Washington families planning sales several years out: the state has enacted a 9.9% income tax on AGI over $1,000,000 starting January 1, 2028 (WA DOR). How it will interact with the capital gains tax is not yet settled, so deferring large sales past 2027 deserves a fresh look before you plan on it.

Which shares to sell first

Lots acquired at different times carry different bases and holding periods into the buyer shares. Choose lots on purpose, using specific identification with your broker, rather than accepting the default.

• Lots held one year or less (for example, RSUs that vested in the last few months) are short-term. Federally, that gain is taxed at ordinary rates of up to 37%, plus 3.8% NIIT, instead of 20% plus 3.8%. Waiting for these lots to pass the one-year mark (IRS Topic 409) can be worth it if the position is not too large to hold a few more months. In California, the state rate is the same either way.
• Lots with little or no gain, such as recent RSU vests, are cheap to sell and reduce concentration at almost no tax cost. Check that your broker’s basis for RSU shares matches the income already reported on your W-2, so you are not taxed twice. See which to sell first, ESPP or RSU shares.
• ESPP lots carry their own holding rules. A sale before the qualifying period ends (two years from the offering date and one year from purchase) is a disqualifying disposition, with part of the gain taxed as ordinary compensation income.

Once you work for the buyer: trading windows and 10b5-1 plans

If you join the buyer, its insider trading policy now governs when you can sell. Many companies allow trades only in short quarterly windows. A Rule 10b5-1 plan lets you set up future sales in advance, while you have no inside information, so they can execute even during a blackout. Under the SEC’s 2022 amendments, an employee who is not a director or officer must wait 30 days between adopting a plan and the first trade; directors and officers wait longer (SEC fact sheet). For a family that wants to sell down over 12 to 24 months, a plan turns a decision you keep postponing into a schedule.

Common mistakes

• Keeping all the buyer stock because the exchange was tax-free.
• Forgetting the unvested buyer RSUs when measuring concentration. They will vest into more of the same stock.
• Selling short-term lots first by default when long-term lots were available.
• Using the broker’s post-merger basis without checking it against Form 8937 and your vest records.
• Assuming Washington residents owe nothing on the sale. The capital gains tax applies above the standard deduction.

What to write down for your children

An acquisition forces a large decision in a short time, and it rarely comes up again in the same form. Write a one-page Decision Memo: what you owned, what the deal offered, how much you kept, how much you sold and why. Years from now your children may face an acquisition of their own employer, or inherit a concentrated position. Your reasoning about risk versus tax is worth more to them than the account statement. Conversations fade. Documentation compounds. Families using the FamilyKnowledge® System keep these memos in one place so the thinking survives.

Frequently asked questions

What happens to your stock when another company buys it?

Your shares are converted into whatever the buyer agreed to pay: cash, buyer shares, or a mix. Cash is a taxable sale at closing. Buyer shares received in a qualifying reorganization are usually tax-deferred, with your basis and holding period carried over. Unvested employee awards follow the merger agreement and your grant terms. The full mechanics are in our acquisition guide.

Is it better to sell before or after an acquisition closes?

In a cash deal, selling before closing gives up the small gap to the deal price, removes the risk that the deal fails, and can move the gain into a different tax year if closing falls in the next year. In a stock deal, selling before closing makes the gain taxable now, while holding through closing defers it and lets you decide later with the buyer’s shares. The right choice depends on your other income that year and on how much deal risk you are willing to carry.

What if I am offered a tender offer instead of a merger?

In a tender offer you choose whether to sell your shares to the buyer at the offered price. Shares that are not tendered are often bought later at the same price in a follow-up merger. See how tender offers work for the steps and deadlines.

Next step

List every buyer share lot with its basis and purchase date, add your unvested buyer RSUs, and calculate the after-tax cost of selling down to a size you would choose. If you would like a second set of eyes on the tax and timing, the Tax & Wealth Assessment from Age Five Family Office™ covers equity compensation, tax management and investment risk for families in California and Washington.

This is general education, and the right move depends on the family’s full picture.

Written by

Kevin Luu

Co-Founder and Chief Learning Officer, Bright Advisers

Kevin has advised high-income W-2 tech and biotech families since 2015, and leads the education-first Age Five Family Office from Brea, California.

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