What Happens to Your ESPP When Your Company Is Acquired
An employee stock purchase plan rarely survives a sale. Here is what happens to the current offering period, your payroll contributions and the shares you already bought.
When a company with an employee stock purchase plan (ESPP) is acquired, the plan usually ends before closing. The current offering period is cut short, a final purchase is made with the payroll money already collected, and any leftover cash is refunded. The exact steps are in the merger agreement’s ESPP clause and your plan document.
An ESPP lets employees buy company stock through payroll deductions, often at a discount. Most plans at US public companies are written to qualify under Section 423 of the Internal Revenue Code, which sets the tax rules described below. Buyers rarely keep a target’s ESPP running, because the target’s shares stop trading at closing.
What happens to the current ESPP offering period?
The current offering period is normally shortened so that a final purchase date falls a few days before closing. Your accumulated contributions buy shares on that date at the plan’s usual discount formula.
Sanofi’s cash acquisition of Dynavax Technologies at $15.50 per share is a typical example. The Offer to Purchase filed with the SEC on January 12, 2026 said the ESPP’s final offering period would end no later than the day before the merger took effect. Money in each participant’s account would buy whole shares on that final date, those shares would be canceled at closing in exchange for $15.50 each, and any money left over would be returned to the participant.
The same agreement froze the plan between signing and closing:
- No new employees could join the ESPP.
- Current participants could not raise their contribution rate.
- No new offering periods could start.
Will I get my ESPP contributions back?
You get back only the money that is not used in the final purchase. Contributions collected before the final purchase date normally buy shares, and what remains (for example, an amount too small to buy one whole share) is refunded.
If the deal is terminated instead of closing, a plan frozen at signing usually restarts under its normal rules. If the plan itself is terminated without a final purchase, plan documents generally require the company to return the contributions. Check the “Termination” or “Corporate Transactions” section of your plan for the exact rule.
| Situation | What usually happens to your payroll money |
|---|---|
| Deal closes, final purchase made | Buys shares on the shortened purchase date; small remainder refunded |
| You withdraw from the plan before the final purchase | Full refund of contributions, under most plans’ withdrawal rules |
| Plan terminated with no final purchase | Contributions refunded |
| You leave the company before the final purchase | Contributions refunded under most plans; no purchase made |
How does the Section 423 discount work?
Under Section 423, the purchase price can be as low as 85% of the stock’s fair market value. Many plans use the lower of the price on the first day of the offering period and the price on the purchase date, then apply the discount. The law also caps purchases at $25,000 worth of stock per calendar year, measured at the price when the option is granted.
When an offering period is cut short for a merger, the formula stays the same; only the purchase date moves. If your plan has a lookback and the deal price is well above the starting price, the final purchase can still be at a deep discount to the deal price.
What is a qualifying vs disqualifying disposition?
A qualifying disposition is a sale made after both holding periods have passed: more than two years after the offering period began (the grant date) and more than one year after the shares were bought. Any sale earlier than that is a disqualifying disposition. IRS Publication 525 sets out how each is taxed.
| Qualifying disposition | Disqualifying disposition | |
|---|---|---|
| Holding periods | Over 2 years from grant and over 1 year from purchase | Either period not met |
| Ordinary income | The lesser of (a) the grant-date discount, or (b) the actual gain from the price you paid | Market value on the purchase date minus the price you paid, even if you later sold for less |
| Rest of the gain or loss | Capital gain or loss | Capital gain or loss, with basis raised by the ordinary income |
| Form you receive | Form 3922 from the employer after the first transfer of ESPP shares |
Does an acquisition count as selling my ESPP shares?
In a cash deal, yes: exchanging your shares for cash at closing is a sale. Shares bought in the final, shortened offering period are converted within days, so they fail the holding periods and are taxed as a disqualifying disposition. Older ESPP shares held long enough can still qualify.
In an all-stock deal that is a tax-free reorganization, the exchange is not treated as a disposition for these rules under 26 U.S.C. 424(c), so the holding periods can continue with the buyer’s shares. Mixed cash-and-stock deals are more complicated. The proxy statement’s section on “Material U.S. Federal Income Tax Consequences” says how the deal is expected to be treated, and our guide to what happens to your shares in a merger covers the basics. For your own return, ask a tax professional.
ESPP shares you already own are ordinary shares at closing. They receive the same cash or stock as every other share, in the brokerage account where the plan deposited them. Treatment of your other awards is covered in our guides to stock options and RSUs in an acquisition.
Bottom line
Keep every Form 3922 and the purchase confirmations from your ESPP broker, because the broker’s Form 1099-B often reports a cost basis that leaves out the ordinary income already counted on your W-2. Publication 525 notes that adjusting that basis on Form 8949 is your responsibility, and getting it wrong means paying tax twice on the same discount.
FAQ
Can I still join the ESPP after a deal is announced?
Usually not. Merger agreements commonly bar new participants and new offering periods between signing and closing, as the Dynavax agreement did.
Can I increase my ESPP contributions before the final purchase?
Most agreements block increases once the deal is signed. You can typically still withdraw or reduce contributions under your plan’s normal rules.
Will the buyer offer its own ESPP?
Some buyers let new employees join their plan at the next enrollment window, but nothing requires it. Ask HR whether and when you become eligible.
How is the final ESPP purchase taxed if the deal is all cash?
The shares are exchanged for cash within days of purchase, which makes the sale a disqualifying disposition. The difference between the market value on the purchase date and the price you paid is ordinary income reported on your W-2.
