A single failed trial can undo years of work in one trading session, and Ionis Pharmaceuticals (IONS) just went through both consecutively.Ionis Pharmaceuticals lost nearly a quarter of its value on July 9 after its heart drug Wainua failed to meet the primary goal of a late-stage trial. The next day brought a second blow from a different corner of Ionis’ drug lineup.For anyone holding the stock or watching the wider Healthcare space, the two-day fall is a reminder of how quickly a biotech project can change.Why Ionis stock crashed after the Wainua trial failureThe trigger was clear. On July 9, Ionis and partner AstraZeneca (AZN) said their Phase 3 CARDIO-TTRansformtrials of eplontersen, sold as Wainua, failed to meet their primary goal in patients with ATTR-CM.ATTR-CM is a heart disease in which misfolded proteins build up in the heart muscle, making it harder for the heart to pump blood. It is a large and fast-growing market, which is why the miss stung so much.More Health Care Stocks:BridgeBio stock jumps after rival heart drug fails key trialEli Lilly’s hottest drugs face a quiet new threatBiotech stock sends Wall Street asurprising signalThe study tested whether adding Wainua to standard care reduces cardiovascular deaths and recurrent heart events over 140 weeks. Unfortunately, it did not, Ionis confirmed in its official release.The stock fell about 24% that day, sliding from a prior close near $86 toward $64.
Ionis shares fell sharply after back-to-back pipeline setbacks in July 2026.SOPA Images / Getty Images
How the Roche exit deepened the Ionis selloffOne bad day can be shrugged off. But two in a row is hard to ignore.According to BioPharma Dìve, Roche said it was ending two Huntington’s disease programs it ran with Ionis on July 10, including the antisense drug tominersen. Ionis shares fell about another 8% after the news.Roche said the tominersen study did not meet its performance goal, and a second early-stage program was stopped over a safety signal from animal testing.Stacked together, the two days erased months of gains. By the July 10 close, IONS sat near $58, down about 29% over five sessions, 24/7 Wall St noted.What Wall Street analysts did to Ionis’ price targetsAnalysts moved fast, and almost all of them cut their target. However, most kept their Buy ratings, which tells you they see the damage as contained rather than fatal.Recent Ionis price target changes:Jefferies: $113 to $90, Investing.com reported (Buy)TD Cowen: $108 to $94 (Buy)Oppenheimer: $110 to $92 (Outperform)BofA Securities: $111 to $90 (Buy)Needham: $105 to $86 (Buy)According to Stocktwits, BofA Securities called the failure a big surprise and tied it to a shifting treatment landscape, as more patients now start on stabilizer drugs early.Which rivals gain the most from the Ionis setbackA drug failure at one company often turns into a win for its competitors. That played out immediately here.Shares of Alnylam Pharmaceuticals (ALNY) and BridgeBio (BBIO) jumped, since the miss reduces near-term competition in the ATTR-CM market.Both companies and Pfizer (PFE) Inc. already sell approved heart therapies, so the Wainua trial failure leaves them more room to grow prescriptions, Benzinga reported.Why the broader Ionis business is not broken yetHere is the part people panicking tend to skip. Wainua itself is not going away.The drug is already approved and generating revenue in more than 20 countries for a separate nerve condition, Yahoo Finance reported. The failed study was about expanding it into heart disease, not defending its current use.Ionis also posted first-quarter revenue of $246 million, and its management guided 2026 revenue to a range of $875 million to $900 million.What Ionis investors should watch over the next few monthsIonis and AstraZeneca plan to present the full CARDIO-TTRansform dataset at the European Society of Cardiology Congress in August, 24/7 Wall St reported.That presentation will show whether a patient subgroup benefited enough to matter.A prespecified subgroup on Wainua alone did show a small but meaningful risk reduction, so the August readout could reset expectations either way.Two later regulatory decisions on other Ionis drugs are also due before year-end, and each one gives the company a chance to prove the franchise runs deeper than one heart trial.Key takeaways for Ionis investors:The Wainua ATTR-CM trial failure, not a business collapse, drove the initial 24% drop.The Roche Huntington’s exit added a second shock and pushed the five-day loss near 29%.Most analysts cut targets but kept buy ratings, signaling contained damage.Watch the August European Society of Cardiology (ESC) data and two year-end regulatory decisions for the real reset.None of this makes IONS a clear bargain or a stock to avoid. The next few catalysts decide what happens with the stock going forward.Related: Lilly quietly hands Chinese partner its cancer drug