Why Did Arcellx (ACLX) Stock Surge 70%? $7.8B Buyout Deal

Shares of Arcellx, Inc. (NASDAQ: ACLX) skyrocketed nearly 78% on Monday, February 23, 2026, after Gilead Sciences announced a definitive agreement to acquire the biotechnology company in a deal valuing Arcellx at approximately $7.8 billion. The offer of $115 per share in cash, representing a 68% premium to Arcellx’s 30-day volume-weighted average price as of February 20, 2026, sent the stock soaring from a prior close of $64.11 to trade above $113.95 in morning session trading.

The deal also includes a contingent value right (CVR) worth an additional $5 per share, payable if anito-cel, Arcellx’s lead CAR-T therapy, reaches cumulative global net sales of at least $6 billion through year-end 2029. Both companies’ boards have approved the transaction, which is expected to close in Q2 2026, subject to regulatory clearance.

Breaking Down the $7.8B Acquisition

The acquisition expands and formalizes a collaboration between Gilead’s Kite Pharma unit and Arcellx that began in 2022, centered on anitocabtagene autoleucel (anito-cel), an investigational BCMA-directed CAR-T cell therapy for patients with relapsed or refractory multiple myeloma.

CAR-T therapy works by extracting a patient’s own immune cells, genetically engineering them to target cancer, and reinfusing them, a cutting-edge approach that has shown significant promise in blood cancers.

By acquiring Arcellx outright, Gilead gains full control of anito-cel, eliminating the existing profit-sharing arrangement, milestone payments, and royalty obligations it previously shared with Arcellx under their partnership agreement. Gilead already held approximately 11.5% of Arcellx’s outstanding common stock prior to the announcement, underscoring the depth of the companies’ existing relationship.

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The CAR-T Therapy Driving the Deal

The FDA has accepted a Biologics License Application (BLA) for anito-cel as a fourth-line treatment for patients with relapsed or refractory multiple myeloma, with a Prescription Drug User Fee Act (PDUFA) action date of December 23, 2026.

The application is backed by results from a Phase 1 study and the pivotal Phase 2 iMMagine-1 trial, positioning anito-cel as a potentially significant competitor in the multiple myeloma space against existing therapies from rivals including Johnson & Johnson. Gilead CEO Daniel O’Day underscored the company’s confidence in the therapy, noting their intention to move quickly to maximize its potential for patients.

Upon FDA approval, the transaction is expected to be accretive to Gilead’s earnings per share in 2028 and beyond, making the $7.8 billion price tag a forward-looking bet on a blockbuster drug.

ACLX Stock Brief: Price, Trends & Key Metrics

As of 10:18 AM EST on February 23, 2026, ACLX was trading at $113.95, up $49.84 (+77.74%) on the day, with an intraday range of $113.85 to $114.26. Volume surged to over 7.2 million shares versus an average daily volume of approximately 1.08 million, reflecting the enormous investor reaction to the buyout news.

The stock’s 52-week range had previously spanned $47.86 to $114.26, meaning today’s gap-up effectively pushed shares to a new all-time high. Year-to-date, ACLX is now up approximately 75%, vastly outperforming the S&P 500’s modest 0.68% YTD gain over the same period.

On the analyst front, Wells Fargo moved to downgrade the stock to Equal-Weight on February 23, setting a price target of $115, effectively the acquisition price, suggesting limited upside beyond the deal terms for investors buying in at current levels.

Disclaimer: The author does not hold or have a position in any securities discussed in the article. All stock prices were quoted at the time of writing.