BioMarin is Buying a Rare-Disease Biotech for Nearly $5 Billion. The Stock Is Jumping.

BioMarin Pharmaceutical has announced a $4.8 billion deal to acquire a smaller biotech, Amicus Therapeutics. (Rafael Henrique/Dreamstime.com)

Key Points

• BioMarin Pharmaceutical acquired Amicus Therapeutics for $4.8 billion, paying $14.50 per share, a 33.1% premium.
• BioMarin’s shares were up 17% following the acquisition announcement, which analysts praised for adding to top-line growth.
• Amicus’s two drugs, Galafold and Pombiliti + Opfolda, generated $599 million in net product revenues over the past four quarters.

The battle-scarred biotech BioMarin Pharmaceutical on Friday announced a $4.8 billion deal to acquire a smaller biotech, Amicus Therapeutics, which sells two drugs that treat rare genetic disorders.

It’s the second acquisition for BioMarin of 2025, which is seeking to diversify its product portfolio as it recovers from the commercial failure of a hemophilia A gene therapy.

Shares of BioMarin, which specializes in treatments for rare genetic disorders, were down 50% since the start of 2023 as of the close of trading on Thursday, and 21% so far this year.

BioMarin will pay $14.50 per share for Amicus, a 33.1% premium over the stock’s Thursday closing price of $10.89, and what BioMarin said was a 58% premium over its 60-day volume-weighted average share price. Amicus shares were trading at $14.20 on Friday morning.

Shares of BioMarin were up 17% on Friday, as analysts praised the deal. “Strategically, it actually makes a lot of sense (even if it’s on the bigger side of what we’d been expecting BMRN to do),” Cantor Fitzgerald analyst Olivia Brayer wrote on Friday. “It immediately adds to BioMarin’s top-line growth – which has been a major focus for investors.”

Amicus’s two products, one called Galafold that treats Fabry disease, and another called Pombiliti + Opfolda that treats Pompe disease, had total net product revenues of $599 million over the past four quarters. Analysts project BioMarin’s 2025 revenues at $3.2 billion.

BioMarin’s CEO, Alexander Hardy, said on a Friday investor call that he believes both of the Amicus drugs have the potential to hit $1 billion in peak sales.

Sales projections for BioMarin have come down sharply in recent years, as expectations around sales of the hemophilia A drug, called Roctavian, have collapsed. In early 2022, before the Roctavian disappointment, FactSet consensus estimates had BioMarin revenues topping $5.4 billion in 2027. Now, analysts are expecting just $3.7 billion in 2027 sales.

The Amicus acquisition comes amid a wave of enthusiasm for the biotech sector at large, as a steady drumbeat of acquisitions, plus shifts in the broader market, have helped push up biotech valuations in a run-up unequaled in recent years. The SPDR S&P Biotech ETF, which tracks the sector, is up more than 45% since the start of July.

BioMarin stock had sat out that run-up before Friday’s announcement. The company’s struggles over the past few years are emblematic of broader pressures across the sector.

One of the older biotechs in existence, founded in 1997, it had its first profitable year in 2020. Early in the decade, BioMarin had focused heavily on Roctavian, which was approved in Europe in 2022, and in the U.S. in 2023. Like many other gene therapies, the treatment has struggled since it came to market. In late 2022, BioMarin said investors should expect 2023 Roctavian sales of between $100 million and $200 million; sales were only $3.5 million that year.

Activist investor Elliott Investment Management intervened in 2023, the longtime CEO retired, and in 2024, the new CEO, Hardy, rolled out a new strategy, which included cost cuts. Earlier this year, BioMarin said it planned to divest Roctavian. Sales of another key product, Voxzogo, which treats a form of dwarfism, are expected to have hit $912 million in 2025, according to FactSet, up from $735 million in 2024.

The Amicus deal is the second this year for BioMarin, after a $270 million acquisition that closed in July to buy a rare disease biotech called Inozyme Pharma. Business development “is about, for us, supplementing the growth rates in the medium term,” Hardy, the CEO, said at an investor conference in November. “We don’t need to buy revenue, we don’t have any large loss of exclusivity events. But we believe that actually assets are worth more in our hands than where they are sitting right now.”

Sales of Amicus’s Galafold are expected to have been $515 million in 2025, according to FactSet. On Friday, Amicus said it had settled intellectual property litigation with two companies seeking to sell generic versions of Galafold that will keep a generic from launching until 2037.

Sales of the company’s other medicine, Pombiliti + Opfolda, are anticipated to have  been $112 million in 2025, according to FactSet.