Why is Arcellx stock up 80% today? Gilead’s $7.8B answer
Arcellx stock (NASDAQ: ACLX) climbed roughly 80% in premarket trade on Monday after Gilead Sciences agreed to buy the cancer-therapy developer in a $7.8 billion all-cash deal.
The stock’s move wasn’t a mystery rally.
The surge was a classic takeover repricing: once Gilead and Arcellx signed a definitive deal at $115 a share, traders quickly bid ACLX up toward that buyout price.
The deal math: $115 cash, plus a $5 “if-it-happens” kicker
Gilead said it will pay $115 per Arcellx share in cash at closing, plus one non-transferable contingent value right (CVR) worth an additional $5 per share if a sales target is met.
A CVR is essentially an IOU tied to a future milestone: shareholders receive additional compensation only if the acquired drug performs well enough after launch.
In this case, the CVR pays out if Arcellx’s lead therapy, anito-cel, reaches at least $6 billion in cumulative global net sales from launch through the end of 2029.
The $115 cash price plus the CVR represented a premium of about 87% to Arcellx’s previous close, which explains why the stock surged toward the takeout price almost immediately.
The transaction is structured as a tender offer followed by a second-step merger at the same consideration, and it has already been approved by both companies’ boards.
Gilead also disclosed it already owns about 11.5% of Arcellx’s outstanding shares.
Gilead’s stock, meanwhile, was modestly lower in premarket trade, about a 1% dip, an often-seen reaction when a large-cap buyer commits billions in cash.
Gilead said the acquisition is expected to be accretive to earnings per share starting in 2028 and beyond, assuming FDA approval for the drug.
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Arcellx stock: The strategic prize
Gilead is paying up for a very specific asset: anitocabtagene autoleucel, known as anito-cel, an investigational BCMA-directed CAR-T therapy for relapsed or refractory multiple myeloma.
CAR-T, short for chimeric antigen receptor T-cell therapy, is a form of personalized cancer treatment where a patient’s own immune cells are engineered to better recognize and attack cancer.
The commercial opportunity is large, but so is the competition.
The multiple myeloma CAR-T category is currently led by Johnson & Johnson and Legend Biotech’s Carvykti, a benchmark that rivals are trying to match on efficacy, safety, and the ability to manufacture at scale.
Arcellx has previously released data that analysts viewed as supportive of anito-cel’s potential in this market, with Fierce Biotech noting comparisons being drawn against Carvykti as datasets have matured.
The timeline is also a key driver of deal urgency.
The FDA is evaluating anito-cel with a decision expected by Dec. 23, 2026, which keeps the story in an active, near-launch window rather than a distant research bet.
Gilead also pointed to the partnership history here as the companies have been collaborators in cell therapy since 2022, and this buyout consolidates control of a program Gilead already knows well.
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