GlobeNewswire·Jul 28, 2026, 12:46 PM ET

Ionis Pharmaceuticals, Inc. (IONS) Faces Investor Scrutiny After Surprise Trial Failure Drives Stock Down 23% – HBSS

Ionis Pharmaceuticals shares fell $20.19 (-23%) on July 9, 2026, after its Phase 3 CARDIO-TTRansform trial for eplontersen failed to meet its primary efficacy endpoint.
AstraZeneca partnered with Ionis on the therapy for transthyretin amyloidosis cardiomyopathy (ATTR-CM), but the addition of eplontersen to standard care did not yield statistically significant benefits.
The trial involved a patient population where 57% received stabilizer treatment at baseline, with an additional 24% initiating stabilizers during the study, a factor analysts noted as driving the endpoint failure.
Market reaction wiped out over $3.3 billion in Ionis market capitalization following the announcement.
Hagens Berman has launched an investigation into whether Ionis was transparent about trial data & design & if the company violated federal securities laws.
Ionis previously described the study as the largest in ATTR-CM & assured investors that study execution was proceeding well before the failure announcement.
The firm encourages investors with substantial losses to submit claims & invites whistleblowers with non-public information to contact them or utilize the SEC Whistleblower program for potential rewards up to 30% of SEC recoveries.