argenx agrees to buy Forte Biosciences for $2.2 billion, adding anti-CD122 antibody to immunology pipeline

The $2.2 billion cash bid for Forte Biosciences, Inc. (NASDAQ: FBRX) puts argenx SE (NASDAQ: ARGX) in focus as the acquirer's next pipeline move. argenx agreed to pay $77 a share, a roughly 40% premium to Forte's Friday close, adding FB102, an experimental first-in-class anti-CD122 antibody, to its immunology portfolio. Both boards have approved the deal, which the companies expect to close in Q3 2026.

The numbers

FBRX shares soared as much as 42% to $77.86 in premarket trading, essentially matching the offer price, a sign the market is confident the deal closes. ARGX, the buyer, fell as much as 0.9% before paring the loss. The buyer's hedge fund base has already been cooling: holders in ARGX dropped from 48 to 42 between the prior quarter and Q1 2026, and the dollar value those funds held fell from approximately $2.33 billion to $1.78 billion. On the Forte side, hedge fund holders climbed from 14 to 23 over the same period, with the dollar value rising from approximately $93 million to $129 million, the kind of accumulation pattern typical of a small, Dallas-based biotech in play.

The setup

argenx's business is built almost entirely around Vyvgart, its blockbuster autoimmune drug. Vyvgart continues to see strong demand across several autoimmune conditions. But analysts project its growth will peak in the early 2030s, and argenx needs its next act. FB102 has shown early promise in vitiligo and celiac disease, two separate autoimmune conditions. argenx sees potential for it to address additional indications beyond those two. Van Lanschot Kempen called it "the right deal at the right time," arguing argenx needs the pipeline depth ahead of Vyvgart's eventual peak. KBC Securities separately said FB102 could become a blockbuster in its own right, fitting argenx's longer-term growth strategy.

The deal history adds context. In December, argenx shares fell after the company discontinued late-stage Vyvgart trials for an eye condition, a reminder that pipeline bets carry real risk. FB102 is early-stage data, and a $2.2 billion price tag prices in a lot of future optionality.

What to watch

Customary closing conditions still need to clear, leaving execution risk between now and the expected Q3 2026 close. For FBRX shareholders, the $77 offer caps upside from here. The next confirmable step is regulatory clearance ahead of the Q3 close.