ADARx Pharmaceuticals became Wall Street's newest biotech darling on Friday, with shares of the San Diego-based drug developer jumping roughly 30% in their Nasdaq debut after the company priced an upsized initial public offering at the top of its range.

The company sold 26.25 million shares at $17 apiece — the ceiling of a marketed $15-to-$17 range — raising approximately $446.3 million, according to ADARx's registration statement filed with the Securities and Exchange Commission. The offer size was increased from an originally planned 21.9 million shares. Stock began changing hands on the Nasdaq Global Select Market under the ticker "ADRX," opening near $22 a share before the offering is set to formally close on September 28.

Pharmaceutical giant AbbVie sweetened the deal further, agreeing to buy up to $100 million of ADARx stock in a concurrent private placement at the same $17-per-share price. That purchase, laid out in the company's pricing announcement, gives AbbVie roughly a 4.9% stake in ADARx once both transactions close, pushing combined gross proceeds to about $535.2 million.

A Bet on Silencing Genes

Founded in 2019, ADARx develops small interfering RNA, or siRNA, therapeutics — drugs designed to "silence" the genetic instructions behind disease-causing proteins rather than blocking them after the fact. Its lead candidate, onvuzosiran, is in late-stage testing for hereditary angioedema, a rare and potentially life-threatening swelling disorder; early data showed it could cut plasma kallikrein levels by as much as 93%, with Phase 3 results expected by the end of 2027 and the possibility of dosing as infrequently as twice a year. A second program, agazisiran, is in mid-stage trials spanning kidney disease, geographic atrophy and a rare blood disorder called paroxysmal nocturnal hemoglobinuria.

AbbVie's private-placement commitment builds on an existing partnership: the two companies struck a collaboration in 2025 worth up to $335 million to co-develop RNA therapies for neurological, immune and oncology conditions, as detailed in ADARx's SEC filing.

J.P. Morgan, Morgan Stanley, TD Cowen and UBS Investment Bank led the offering as joint book-running managers, with LifeSci Capital also acting as a book-runner. Underwriters were granted a 30-day option to buy up to 3.9 million additional shares.

The debut is being read on trading desks as a milestone for a niche corner of biotech that had gone quiet. As BioPharma Dive reported, ADARx is the first RNAi-focused company to price a traditional U.S. IPO in more than a decade and the only RNA-targeted biotech to go public in nearly two years. It arrives amid the strongest year for biotech IPOs since 2021, with roughly 22 drug companies pricing offerings in 2026, according to IPO tracker Renaissance Capital.

That appetite has been selective, however. Electra Therapeutics, another biotech that upsized its IPO to $350 million earlier this year, has seen its shares fall roughly 21% since debuting — a reminder that investors are still pricing risk carefully even as the IPO window reopens.

For ADARx, the next catalysts are clinical, not financial: Phase 3 data on onvuzosiran due by the end of 2027 will determine whether Friday's warm reception from public-market investors translates into a durable, profitable therapy — and whether AbbVie's expanded bet pays off.