argenx stock to buy Unnatural Products for up to 1.15 billion dollars

Argenx announced on Monday, November 9, 2026, that it had agreed to acquire Unnatural Products, Inc. (UNP), a Santa Cruz, California-based biotechnology company developing macrocyclic peptides. The announcement was published at 07:00 CET and was reported in a Business Insider release page carrying the companies' transaction announcement.

Argenx already owns a minority stake in UNP and plans to acquire the remaining shares. The agreement assigns an upfront payment of 550 million US dollars in cash, plus up to 595 million US dollars tied to development and regulatory milestones. The potential total consideration is therefore up to 1.15 billion US dollars, although the contingent payments depend on future program progress.

Platform broadens drug discovery

UNP has built a discovery platform for macrocyclic peptides using parallel experimentation and machine learning. These molecules are intended to address biological targets that can be difficult to reach with conventional medicines. Argenx said the technology complements its antibody engineering and could support the development of oral or long-acting treatments for serious immune-mediated diseases.

Chief Executive Officer Karen Massey said the acquisition supports argenx's next phase while preserving the two companies' more than two-year working relationship. In the announcement, she described UNP's capabilities as complementary to antibody engineering and linked the combination to new possibilities for oral and long-acting medicines.

UNP's team and leadership are expected to remain in Santa Cruz after completion, which will serve as argenx's peptide discovery hub. UNP will continue its discovery work within an agreed strategic framework, while argenx contributes clinical development and commercialization capabilities.

Closing remains subject to conditions

The boards of both companies have approved the transaction. Completion is expected by the end of 2026, subject to customary closing conditions. The agreement has not yet closed, so its financial and pipeline effects remain dependent on completion and on the achievement of the specified milestones.

argenx stock traded at 847.80 euros on Lang & Schwarz at 10:01 CET on Monday, November 9, 2026; the real-time quote of argenx stock is available here.

The broader European market backdrop is available in Current market reports.

More news and analyses on argenx stock will follow developments in the acquisition, its closing conditions and the progress of the combined discovery strategy.