AstraZeneca Made a $10 Billion Approach for Rhythm Pharmaceuticals, Reports Say; RYTM Jumps 28%

AstraZeneca AZN made an offer valued at about $10 billion to acquire Rhythm Pharmaceuticals RYTM, the Wall Street Journal reported on Wednesday, putting the bid at $124 per share and saying it was made last month. Reuters, citing three people familiar with the matter, described a non-binding proposal of as much as $134 a share including payments tied to milestones. AstraZeneca declined to comment and Rhythm did not respond to Reuters, so this is a reported private approach rather than an announced deal.

Rhythm shares closed up 28% at $110.68, giving the company a market value of about $7.64 billion. The $124 figure is roughly a 43% premium to Tuesday's $86.44 close and still about 12% above where the stock finished on Wednesday, a gap that suggests investors are pricing real uncertainty about whether a deal is agreed and on what terms.

Rhythm is not a mass-market weight-loss company. Its drugs target rare genetic and hypothalamic forms of obesity rather than the broader market led by GLP-1 drugs, and its approved medicine, Imcivree (setmelanotide), gained an expanded FDA label in March for acquired hypothalamic obesity, a rare form caused by brain damage. According to Reuters, AstraZeneca would pursue the deal through Alexion, the rare-disease unit it bought for $39 billion in 2021, and Jefferies analyst Michael Leuchten called a focus on rare-disease assets that fit AstraZeneca's "existing footprint" "entirely sensible".

What to watch: whether either company confirms talks or a formal offer emerges, whether the price is structured as cash plus milestone payments (which would reconcile the $124 and $134 figures), and how Rhythm's board responds. A deal of this size would be modest for AstraZeneca, valued at about $292 billion, but would give it a commercial position in obesity through a rare-disease route rather than a head-on GLP-1 challenge.