ADARx Pharmaceuticals prices $446m IPO on Nasdaq

The San Diego siRNA biotech raised up to $535m including an AbbVie cornerstone placement, valuing one of 2026's larger biotech listings.

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ADARx Pharmaceuticals has priced its initial public offering at $17.00 per share, raising gross proceeds of approximately $446.3 million from the sale of 26,250,000 shares of common stock. The San Diego-based company, which develops small interfering RNA therapeutics, is due to begin trading on the Nasdaq Global Select Market under the ticker "ADRX" from 25 September 2026, with the offering expected to close on 28 September.

The IPO was upsized from its original size, reflecting demand from institutional investors. Underwriters led by J.P. Morgan, Morgan Stanley, TD Cowen and UBS Investment Bank retain a 30-day greenshoe option to purchase up to an additional 3,937,500 shares at the offer price, which could add a further $66.9 million to gross proceeds.

AbbVie anchors a concurrent private placement

Running alongside the IPO is a concurrent private placement in which AbbVie has agreed to purchase shares at the same $17.00 price, capped at $100 million and calibrated so that the pharma major holds approximately 4.9% of ADARx's outstanding shares on closing. Combined gross proceeds from the IPO and the placement are expected to reach approximately $535.2 million before fees, absent any greenshoe exercise.

The AbbVie stake is not simply a financial investment. The two companies already have a collaboration and licence option agreement covering siRNA therapeutics in neuroscience, immunology and oncology. AbbVie's willingness to take a meaningful equity position at the IPO price signals continued confidence in the platform and provides ADARx with a large-cap validation that smaller RNA-focused companies rarely enjoy at the point of listing.

Pipeline and competitive context

ADARx describes itself as a late-stage clinical company with a pipeline spanning complement-mediated diseases, cardiovascular conditions, thrombosis, central nervous system disorders and metabolic disease, including obesity. The breadth of that therapeutic coverage is characteristic of well-capitalised RNA interference platforms, and positions ADARx against established players such as Alnylam Pharmaceuticals, which has several approved siRNA products, and a cohort of mid-stage rivals including Arrowhead Pharmaceuticals and Dicerna (now part of Novo Nordisk).

The siRNA field has matured considerably since Alnylam's first approvals, and investors are increasingly able to differentiate on the basis of delivery technology, tissue targeting and dosing durability rather than platform novelty alone. ADARx's prospectus, filed with the SEC, will contain the clinical and preclinical detail that will allow analysts to benchmark its candidates against those of competitors. The company's stated focus on highly potent and durable candidates suggests a chemistry-first differentiation strategy, though the press release does not disclose specific clinical readouts or Phase designations for individual pipeline assets.

The scale of this raise is notable in a year when many biotech IPOs have been cautiously sized. At over $535 million combined, ADARx enters the public markets with substantial runway, reducing the near-term dilution risk that has weighed on smaller debutants. Investors will now focus on expected clinical milestones and whether AbbVie's option rights across the collaboration convert into full licences, which would represent a significant non-dilutive revenue event.

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