AstraZeneca made non-binding offer of about $10 billion for Rhythm Pharmaceuticals, sources say; Rhythm shares close up 28%

AstraZeneca made an offer of about $10 billion to acquire Rhythm Pharmaceuticals, according to three people familiar with the matter. The proposal was non-binding and valued Rhythm at as much as $134 a share, including payments tied to milestones, the people said.

An AstraZeneca spokesperson declined to comment. Rhythm did not respond to a request for comment. Nothing here is confirmed by either company.

What the offer reportedly looks like

The Wall Street Journal reported earlier Wednesday, Nov. 4, that AstraZeneca had made a $124-per-share offer for Rhythm last month. The $134 figure is the high end of what the three people described, and it includes milestone payments, meaning part of the price depends on future events rather than cash up front.

Neither company has said whether the $124 and $134 figures describe one proposal or two. Rhythm's board has not said whether it rejected, countered or is weighing the offer.

Rhythm's stock closed Wednesday up 28% at $110.68, which gives the company a market value of about $7.64 billion. By our math, $134 is roughly 21% above that close and about 55% above where the stock stood before the jump. The gap between a $7.64 billion market cap and a roughly $10 billion offer shows how much of the price rides on how the headline figure is built.

Why Alexion, and why Rhythm

Two of the people said AstraZeneca would pursue the deal through Alexion, its rare-disease unit. AstraZeneca bought Alexion for $39 billion in 2021 to expand beyond its core oncology and biopharmaceutical business. Alexion has since become the centerpiece of the company's push into specialty medicines.

Rhythm makes treatments for rare neuroendocrine and metabolic disorders, including severe forms of obesity. In March, the U.S. Food and Drug Administration expanded the use of its drug Imcivree to a rare form of obesity caused by brain damage. It is the first treatment approved in the United States for that condition.

Jefferies analyst Michael Leuchten said AstraZeneca's approach of looking for rare-disease assets that fit its "existing footprint is entirely sensible in our view." He also said that, historically, Rhythm "could be viewed as addressing ultra-rare genetic obesity," and that the March 2026 approval in acquired hypothalamic obesity "materially changes that proposition."

AstraZeneca's backdrop

AstraZeneca, with a market value of $292 billion, has had a rough few months. The company faced clinical trial setbacks, and reports of a potentially transformative deal with U.S. rival Bristol Myers Squibb weighed on its shares. CEO Pascal Soriot is trying to move investors' attention back to growth.

The Journal reported that AstraZeneca had expressed interest in Rhythm before and renewed its pursuit in recent months.

The obesity market angle

Obesity is one of the most sought-after areas in the drug industry. Demand for treatments from Novo Nordisk and Eli Lilly is strong, and expectations are that sales could top $100 billion a year over the next decade.

Rhythm is not playing in that mass market. Its therapies target rare genetic and brain-injury-related forms of obesity, not the broad weight-loss market. An acquisition would still give AstraZeneca an established commercial presence in obesity while adding to its rare-disease lineup.

What comes next

A non-binding proposal commits no one. It can be raised, rejected, withdrawn or never acknowledged. The open questions are whether Rhythm's board engages, whether the price moves toward the $134 ceiling, and how much of it is tied to milestones Rhythm has yet to hit. Neither company has said when, or whether, it will address the reports.