Lonza to Buy Five Merck KGaA U.S. Plants in Push Into Antibody-Drug Conjugates

As of Thursday, Nov. 5, 2026.

Swiss contract manufacturer Lonza has agreed to buy five U.S. manufacturing plants from Merck KGaA, a deal aimed at expanding its American footprint in some of the fastest-growing areas of drug production, according to BioSpace. The deal was announced Tuesday, Nov. 3, and is expected to close in mid-2027.

What Lonza is buying

The five sites span several specialized manufacturing steps, BioSpace reported:

• St. Louis, Missouri: a bioconjugate plant.
• Madison and Verona, Wisconsin: high-potency payload-linker facilities.
• Carlsbad, California: a viral vector plant.
• Indianapolis, Indiana: an aseptic fill-finish site.

About 1,100 employees will transfer to Lonza. After the deal closes, Lonza will have more than 6,000 employees across nine U.S. sites, according to BioSpace.

The price tag

Lonza did not disclose an exact price. It described the valuation as being in the low to middle hundreds of millions of Swiss francs. On a Tuesday conference call, CEO Wolfgang Wienand said a figure in the middle of a range of CHF 100 million ($122 million) to CHF 600 million ($732 million) would be about right, BioSpace reported.

Lonza expects the acquired sites to contribute about CHF 250 million ($305 million) in sales in 2028. The plants will initially be less profitable than the rest of Lonza, but the company expects their margins to catch up by the time sales peak in the mid-2030s. Wienand said capacity use at the sites is well below potential.

Why antibody-drug conjugates matter

The deal’s main strategic focus is antibody-drug conjugates, or ADCs. These medicines link an antibody, which seeks out specific cells such as tumor cells, to a potent drug payload that is delivered directly to those cells. Making them requires several specialized steps, including producing the payload, attaching it with a chemical linker and filling the finished product under sterile conditions.

Lonza’s ADC work is currently centered on its site in Visp, Switzerland. According to BioSpace, the new plants would give Lonza end-to-end U.S. manufacturing for ADC drug substance, letting it work with customers earlier in development and offer clinical and commercial production on both sides of the Atlantic.

Wienand cited forecasts that the global bioconjugation market will grow from about $30 billion today to about $110 billion by 2033. Analysts at William Blair called the purchase another highly attractive strategic acquisition that strengthens Lonza across several high-growth types of medicine, according to BioSpace.

How this differs from Lonza’s last U.S. plant deal

Lonza bought a U.S. plant from Roche in 2024, and that deal came with an agreement to keep supplying the drugs Roche made there. BioSpace reported that the Merck KGaA transaction is different. Christian Seufert, Lonza’s head of advanced synthesis, cautioned against assuming a supply contract exists, saying the business was primarily focused on third-party sales.

That means Lonza’s return on the deal depends more on winning new customers and filling unused capacity than on a guaranteed anchor client.

The bigger picture for drug manufacturing

Contract development and manufacturing organizations, or CDMOs, make drugs on behalf of pharmaceutical and biotech companies. Many smaller biotechs do not own factories, so CDMOs with the right capacity in the right locations can become key partners.

Wienand also signaled that Lonza is open to more deals. He said the company “will not hesitate” to pursue another attractive takeover target while it integrates the five sites, according to BioSpace.

Also this week

The Lonza deal came during a busy stretch of third-quarter earnings. Pfizer on Tuesday reported roughly flat revenue of $16.6 billion and raised its full-year revenue guidance by $1.5 billion, to $62 billion to $64 billion, BioSpace reported. Also on Tuesday, BioSpace reported that Novartis had pulled back from a $772 million brain-delivery alliance with BioArctic.

Sources: BioSpace.

How an ADC Is Made, Step by Step

The five sites in this deal map onto distinct stages of manufacturing for complex medicines. For an antibody-drug conjugate, the production chain typically includes:

1. Antibody production. The antibody is grown in large bioreactors using mammalian cells, then purified. This step is often performed at a separate biologics facility.
2. Payload and linker synthesis. The cell-killing payload and the chemical linker are made through multi-step chemistry. Because payloads are extremely potent, even tiny amounts can be hazardous, so facilities need specialized containment to protect workers and prevent cross-contamination.
3. Conjugation. The payload-linker is chemically attached to the antibody under tightly controlled conditions. Consistency in how many payload molecules attach to each antibody is a key quality measure.
4. Purification and testing. The conjugate is purified to remove unattached payload and other impurities, then tested against detailed specifications.
5. Fill-finish. The drug substance is filled into vials under sterile, or aseptic, conditions. Many ADCs are freeze-dried for stability.
6. Release. Quality teams review data from every step before a batch can be shipped for clinical or commercial use.

When different steps happen at different companies or countries, each handoff adds shipping, scheduling and regulatory coordination. Keeping the chain in one network is the essence of the end-to-end offering described above.

A Quick Primer on Viral Vectors

The Carlsbad site makes viral vectors, which are used in gene therapies and some cell therapies. A viral vector is a virus that has been modified so it cannot cause disease but can still deliver genetic material into cells. Common types include adeno-associated viruses, used in many in vivo gene therapies, and lentiviruses, often used to engineer cells such as CAR-T therapies. Vector manufacturing is technically demanding and has historically been a bottleneck for these treatments.

What Biotechs Typically Ask When Choosing a CDMO

• Capability fit. Does the manufacturer have experience with this modality, scale and potency level?
• Capacity and timing. When can production slots be reserved, and how firm are they?
• Regulatory record. What is the site’s inspection history with the FDA and other regulators?
• Technology transfer. How will processes move from the developer’s lab or a previous manufacturer, and how long will it take?
• Location. Does a U.S. site matter for supply security, logistics or customer preferences?
• Continuity. If ownership of a site changes, how are existing contracts and teams handled?

Questions Readers Ask

Why does capacity utilization matter so much?

Manufacturing plants have high fixed costs. Sites running well below capacity spread those costs over fewer batches, which lowers margins. Filling idle capacity can improve profitability substantially, which is central to Lonza’s expectation that margins will catch up.

What does “high-potency” mean in manufacturing?

It refers to substances that are biologically active at very low doses, requiring special handling, equipment and air controls.

Why would a seller part with plants?

Companies sometimes divest manufacturing that is underused or not central to their strategy, freeing capital and management attention for other priorities.

This article is for general information only and is not investment advice.