When a company you own is acquired, your shares are converted into cash, shares of the acquiring company, or a combination of the two, and what happens to stocks when companies merge is dictated entirely by the deal terms laid out in the merger agreement. A cash deal ends your investment with a fixed payout per share. A stock deal swaps your old shares for new ones and keeps you invested in the combined company. A mixed deal does some of each. Your tax bill, your timeline, and whether you have any say all follow from that structure.
The Three Forms of Payment
Every merger falls into one of three categories, and each puts you in a different position.
In an all-cash deal, the acquirer buys every outstanding share for a fixed dollar amount. Cash lands in your brokerage account, you have no ongoing exposure to the combined company, and there’s no guesswork about what the acquirer’s stock does afterward. It’s the simplest outcome.
In an all-stock deal, you receive shares of the acquiring company based on a predetermined exchange ratio. Nothing gets paid out at closing. You become an owner of the larger combined entity, and the value of your holding rises or falls with the acquirer’s stock from that day forward. You gain the ability to defer taxes on any gain. You also now hold a different company, with different management, strategy, and risk.
Mixed cash-and-stock deals split the payment. You might receive $15 in cash and 0.30 shares of the acquirer for each share you held. The cash gives you immediate liquidity while the stock keeps you invested. This hybrid has become increasingly common because it lets the acquirer preserve cash while still offering shareholders some certainty of value.
How the Exchange Ratio and Premium Work
Any deal involving stock specifies an exchange ratio: the number of acquirer shares you receive for each target share. A ratio of 0.50 means one new share for every two old shares. A ratio of 2.0 means two new shares for each old one. The ratio is set to deliver the agreed value based on share prices at the time of negotiation.
Most exchange ratios are fixed at signing, so the acquirer locks in how many shares it will issue regardless of what happens to its stock price between signing and closing. That’s good for you if the acquirer’s stock rises during that period, and bad if it drops. Some deals use a floating ratio that adjusts to deliver a fixed dollar value per share, shifting stock-price risk back to the acquirer. Fixed ratios are far more common in large transactions.
The offer almost always includes a premium over the target’s pre-announcement trading price. Acquisition premiums typically range from 20% to 30% above the unaffected share price, though they can run higher or lower depending on competitive pressure and growth prospects. If your stock traded at $20 before the announcement and the acquirer offers $26 per share, that’s a 30% premium. In a stock deal, the exchange ratio is set to deliver that $26 of value based on the acquirer’s stock price.
Fractional Shares
The math rarely comes out to whole shares. If you held 75 shares and the exchange ratio is 0.45, you’re entitled to 33.75 shares of the acquirer. Since you can’t hold three-quarters of a share in a regular brokerage account, the acquiring company pays you cash for the fractional portion at the market price. You’ll receive 33 whole shares plus a small cash payment for the 0.75 fraction. That cash-in-lieu payment is a taxable event even in an otherwise tax-deferred stock deal.
What You’ll See in Your Brokerage Account
For most retail investors, the exchange is automatic. Your broker handles the mechanics of surrendering old shares and receiving the new consideration. Within a few business days after closing, the cash or new shares appear in your account. The target’s ticker is delisted, and the old position is simply replaced. You don’t need to file paperwork or take action unless you’re exercising appraisal rights.
Timing matters, though. Between announcement and closing, the target’s stock jumps toward the offer price but rarely reaches it. The gap reflects the market’s assessment of the risk the deal doesn’t close: regulatory rejection, shareholder disapproval, or a financing failure. Selling right after the announcement locks in most of the gain but sacrifices the remainder. Holding through closing captures the full offer price but exposes you to the possibility the deal collapses.
Most deals also require a shareholder vote, and the company sets a record date determining who’s eligible. If you owned shares on that date, you’ll receive proxy materials and a ballot. Larger deals must also clear antitrust review, which can add months if regulators request additional information. Some acquisitions bypass the vote by using a tender offer, in which the acquirer goes directly to shareholders with an offer to buy at a specified price. If you receive a tender offer, you’ll need to actively decide whether to tender by the deadline. Inaction means you don’t participate in the initial offer, though you’ll still receive the merger consideration once the acquirer completes the follow-on merger.
Tax Consequences
Tax treatment hinges on what you receive. Cash triggers a tax bill. Stock can defer one. Mixed deals split the difference.
All-Cash Mergers
An all-cash merger works like selling your stock. Subtract your cost basis from the cash you received, and the difference is your capital gain or loss. If you held the shares more than a year, you pay long-term capital gains rates. Less than a year means short-term rates, which match your ordinary income bracket. Most brokers report the gain on your 1099-B.
All-Stock Mergers
When you receive only stock of the acquirer, the exchange can qualify as a tax-free reorganization under Internal Revenue Code Section 368. If the deal qualifies, Section 354 provides that you recognize no gain or loss on the exchange.1Office of the Law Revision Counsel. 26 USC 354 – Exchanges of Stock and Securities in Certain Reorganizations
The tax doesn’t disappear, though. Under Section 358, the original cost basis of your old shares carries over to the new shares.2Office of the Law Revision Counsel. 26 USC 358 – Basis to Distributees If you paid $10 per share years ago and receive acquirer stock now worth $30, you don’t owe taxes today, but your basis in the new shares remains $10. When you eventually sell, you’ll owe tax on the full gain then.
Mixed Deals and Boot
A mixed cash-and-stock deal is partially taxable and partially tax-deferred. The cash portion is called “boot,” and receiving it triggers gain recognition. Under Section 356, you recognize gain only up to the lesser of the boot received or the total gain realized on the exchange.3Office of the Law Revision Counsel. 26 USC 356 – Receipt of Additional Consideration You won’t be taxed on more gain than you actually have, but you can’t defer the portion attributable to cash.
Your basis in the new shares gets adjusted. Under Section 358, start with your original basis, subtract the cash received, and add back any gain recognized. That adjusted basis then follows the new shares until you sell.
The cash-in-lieu payment for fractional shares is also taxable, even in an otherwise tax-deferred stock deal. The amount is small, but it’s treated the same way as boot and must be reported.
Employee Stock Options and RSUs
If you hold options or RSUs through the acquired employer, treatment of your equity compensation is negotiated as part of the merger agreement. The outcome depends heavily on whether your grants are vested and on the specific deal terms. The merger proxy is required to disclose how equity awards will be handled, so check there for the specifics.
Vested stock options are typically handled one of three ways: cashed out at the difference between your strike price and the deal price, converted into equivalent options in the acquirer, or cancelled. Cancellation usually only happens when options are underwater, meaning your strike price is higher than the deal price and they’re worthless anyway. Vested RSUs are generally treated like regular shares and converted into whatever consideration other shareholders receive.
Unvested equity is where things get less predictable. The acquirer might accelerate your vesting, converting unvested grants into vested ones that pay out at closing. It might substitute new grants in the acquirer’s stock on a comparable vesting schedule. It might cancel unvested grants outright. Some agreements convert unvested equity into a cash payment subject to a new vesting schedule tied to continued employment, which serves as a retention tool.
Many companies issue RSUs with “double-trigger” vesting, requiring both a time-based condition and a liquidity event like an acquisition. If your RSUs have a double-trigger provision and the merger satisfies the event trigger, the time-based portion that has already elapsed typically vests and pays out at closing. The remainder may convert to acquirer equity or cash with a continued vesting schedule.
If You Think the Price Is Too Low
Most states give shareholders who believe the merger undervalues their stock the right to reject the deal and ask a court to determine “fair value.” This is called appraisal or dissenters’ rights, and it exists as a safeguard against controlling shareholders forcing through a deal at a lowball price.
Exercising appraisal requires strict procedural compliance. You must not vote in favor of the merger, and you must deliver a written demand for appraisal before or shortly after the vote, depending on the state and how the merger was approved. Deadlines are tight. In many jurisdictions, you have roughly 20 days from the date of the required notice to file your demand. Miss it and the right is forfeit.
The practical reality is that appraisal is expensive and risky. You fund litigation out of pocket, and the process can drag on for years. A court may determine your shares are worth more than the merger price, or it may conclude they’re worth less. You’re locked out of the merger consideration while the case is pending. For most retail investors holding a modest position, the costs and risks make appraisal impractical. It exists primarily as a check on deal pricing, and the threat of litigation sometimes pushes acquirers to raise their bids before a case ever gets to court.
If the Deal Falls Through
Not every announced merger closes. Deals collapse when regulators block them, shareholders vote them down, financing fails, or one party triggers a termination clause. When a deal dies, the target’s stock typically drops sharply, often falling back to or below its pre-announcement price. If you bought shares after the announcement at the elevated price, you’ll be sitting on a loss.
Merger agreements typically include a breakup fee, usually 2% to 4% of the deal value, paid to the target company if the acquirer walks. That fee cushions the company’s balance sheet but doesn’t reach shareholders directly and doesn’t prevent the stock from falling. Failed deals sometimes attract competing bidders, and a rival can step in with a higher offer that pushes the stock above the original deal price. Banking on that is speculation, not strategy. The more common outcome is a painful reset to pre-announcement levels while management regroups.