Amicus Therapeutics, Inc. (NASDAQ: FOLD) ended Friday’s session (December 19, 2025) in a very different place than it started: the stock re-priced into “deal mode” after BioMarin Pharmaceutical (NASDAQ: BMRN) announced a definitive agreement to acquire Amicus in an all-cash transaction valued at roughly $4.8 billion. BioMarin Investors+2Reuters+2
With U.S. markets closed on the weekend, the “tomorrow open” investors are thinking about is really the next trading session on Monday, December 22, 2025—and the key question isn’t “growth vs. pipeline” anymore. It’s deal probability vs. deal timeline (and whether a rival bid emerges). SEC+1
What happened to Amicus Therapeutics stock on Dec. 19, 2025?
FOLD surged roughly 30% on the day as the market digested the buyout terms. Reuters reported the stock jumped about 30% following the announcement, and Investor’s Business Daily pegged the move at +30.2% to about $14.18, putting shares within striking distance of the $14.50 cash offer price.
By late Friday trading, FOLD was hovering around $14.18, according to the consolidated quote data available after the close.
Why that matters: when a public company agrees to be acquired for cash, the stock typically trades just below the offer price until closing—reflecting (1) the time value of money and (2) the risk the deal fails to close. On Friday night, the gap from roughly $14.18 to $14.50 implied a discount of about $0.32 per share (roughly ~2%), suggesting the market is treating this as a high-probability transaction but not a guaranteed one.
The headline driver: BioMarin to buy Amicus for $14.50 per share in cash
The core news investors traded Friday is straightforward:
- Buyer: BioMarin Pharmaceutical Inc.
- Target: Amicus Therapeutics, Inc.
- Consideration:$14.50 per share in cash
- Value: total equity value about $4.8B
- Timing: expected close Q2 2026 (subject to approvals and conditions)
Both boards approved the deal, and Amicus’ board unanimously recommended shareholders vote in favor.
What BioMarin is buying: two marketed rare-disease franchises and a late-stage asset
BioMarin highlighted that it will gain:
- Galafold (migalastat) for Fabry disease
- Pombiliti (cipaglucosidase alfa-atga) + Opfolda (miglustat) for Pompe disease
- U.S. rights to DMX-200, described as a Phase 3 asset for focal segmental glomerulosclerosis (FSGS)
BioMarin also stated the two marketed products generated $599 million in revenue over the past four quarters, a number repeated across deal coverage and the company’s announcement materials.
Financing: “not subject to financing” is a big deal for deal risk
For FOLD shareholders, one of the most important lines in the deal announcement is that the transaction is not subject to financing conditions. That typically lowers the risk that markets tightening—or a lender backing away—kills the deal.
BioMarin said it intends to finance the acquisition with cash on hand plus roughly $3.7 billion of non-convertible debt financing, and that a Morgan Stanley affiliate provided a bridge commitment for that amount.
The “new details” investors got from the SEC filing (and why they matter after the bell)
Beyond the press release headlines, Amicus filed an 8-K outlining key mechanics and deal protections. Here are the parts that matter most going into the next session:
1) What happens to shares and equity awards
- Each common share (with typical exceptions) converts into the right to receive $14.50 in cash at closing.
- In-the-money options get cashed out based on the difference between $14.50 and the strike price; out-of-the-money options get canceled without consideration. RSUs and PSUs are converted to cash payments tied to $14.50 (with PSUs based on specified performance levels).
2) Closing conditions investors should watch
The 8-K lists customary conditions, including:
- Shareholder approval (majority of outstanding common stock)
- HSR Act waiting period expiration/termination and other specified antitrust/FDI clearances
- Absence of certain restraints and no continuing Material Adverse Effect
3) Timeline: proxy filing and an outside “end date”
Amicus said it expects to close in Q2 2026 and will file a preliminary proxy statement within 20 business days of the merger agreement date.
The merger agreement also defines an outside date: if the deal hasn’t closed by June 19, 2026, either party can terminate—with automatic extensions in certain situations if antitrust/FDI approvals are the main remaining hurdle (extending to September 19, 2026 and potentially December 19, 2026).
4) The breakup fee: $175 million
If the deal is terminated under specified circumstances, Amicus may owe BioMarin a $175 million termination fee—including scenarios involving a superior offer, a recommendation change, or certain solicitation-related breaches, among other defined cases.
That fee is one reason the market may be assigning a relatively high close probability: it’s a meaningful deterrent to casually walking away, while still leaving room for a truly superior bid.
The “other” major development Friday: Galafold patent litigation resolution and a long runway claim
BioMarin’s announcement also disclosed that Amicus resolved patent litigation tied to generic challenges for Galafold. The company said it entered license agreements with Aurobindo and Lupin to allow U.S. generic entry starting January 30, 2037 (if FDA-approved and absent certain customary exceptions), and stated that—based on these settlements—U.S. exclusivity for Galafold is expected through January 2037.
For deal math, that matters because it can make future cash flows from Galafold look more predictable—exactly the kind of de-risking that helps a buyer justify paying cash at a premium.
Why FOLD is now trading like a merger arbitrage stock
Going into Monday, the biggest practical shift for Amicus investors is that FOLD has largely stopped trading on:
- quarterly beats/misses,
- long-term pipeline probability, or
- “what is a fair standalone valuation?”
Instead, it’s now mostly trading on:
- Deal spread: how far FOLD sits below $14.50
- Deal risk: regulatory, shareholder, or litigation friction
- Deal time: how many months until cash is actually paid
Amicus itself reinforced this “keep trading until close” reality in its shareholder materials, noting the stock will continue to trade on Nasdaq prior to closing and shareholders will receive $14.50 per share at closing through normal brokerage channels. SEC
Today’s analyst and media takeaways investors are reacting to
While the deal terms are the story, Friday’s coverage did highlight how Wall Street is framing the transaction:
- Reuters emphasized BioMarin’s strategic push deeper into rare metabolic diseases, the cash-and-debt financing plan, and management’s expectation that the transaction will add revenue immediately after closing and become accretive to adjusted profit within 12 months.
- The Wall Street Journal highlighted the $4.8B cash value, the two commercial products (and roughly ~$600M in recent revenue), and positioned the deal within a broader uptick in biotech M&A activity.
- Investor’s Business Daily reported that analysts at firms including Leerink, Oppenheimer, and Needham viewed the combination as strategically complementary—especially around BioMarin’s global infrastructure and enzyme-therapy footprint.
- Several outlets also reported the typical post-deal analyst behavior: price targets converge toward the offer price (e.g., Cantor Fitzgerald lowering its target to $14.50 and reiterating a neutral stance, per widely circulated summaries).
What to watch before the next market open
Here’s the practical checklist for Monday’s open (and the days immediately after), based on what moved FOLD Friday and the deal mechanics disclosed so far:
Watch the spread to $14.50
If FOLD opens materially below Friday’s late price and the spread widens, it can signal rising perceived risk (or simply lower liquidity). If it trades closer to $14.50, it suggests confidence in approvals and timeline.
Scan for “superior offer” chatter—but don’t assume it’s coming
The merger agreement includes typical no-solicitation restrictions with fiduciary-duty exceptions. That means a rival bid is possible in theory, but not guaranteed in practice. Any credible competing bid headline would likely be the only way FOLD meaningfully trades above the deal price before closing.
Regulatory and shareholder vote milestones
The key gating items are:
- HSR/antitrust processes
- Amicus shareholder approval
- The proxy and special meeting schedule
Deal-protection terms that shape downside risk
Traders will keep referring back to:
- the $175M termination fee, and
- the June 19, 2026 end date (plus potential extensions)
Litigation risk management: the forum selection amendment
It’s common for merger deals to attract shareholder lawsuits. Amicus’ board adopted a forum selection bylaw amendment designating Delaware courts (and, for certain Securities Act claims, U.S. federal district courts) as exclusive forums—an attempt to control where such disputes are heard.
The bottom line for Amicus stockholders heading into Monday
As of after-hours Friday, Amicus Therapeutics stock is primarily a bet on deal completion at $14.50 per share in cash in Q2 2026—not a bet on standalone upside. The market already priced in most of the premium on Friday, leaving investors with a narrower, more event-driven profile: modest upside to the offer price (unless a higher bid appears), and downside tied to regulatory delays, shareholder turbulence, or a deal break.
If you want, I can also write a separate companion piece focused on BioMarin (BMRN)—because Monday’s trading could be just as much about whether investors buy BioMarin’s accretion/financing story as it is about Amicus’ takeout price.
