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Here's Why Ionis Pharmaceuticals' Stock is Down 28.5% Post Q3 Earnings

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Key Takeaways

  • Ionis shares fell 28.5% as slower Tryngolza sales and weak Wainua royalties disappointed investors.
  • Tryngolza's 2026 sales guidance was cut by 50-55% to approximately $50 million.
  • Ionis delayed its positive cash flow target to 2029, while Dawnzera sales grew 40% sequentially.

Shares of Ionis Pharmaceuticals (IONS - Free Report) came under significant pressure despite its better-than-expected third-quarter 2026 earnings results. Investors were largely disappointed by the slower-than-expected launch of Tryngolza and the substantial reduction in the drug’s full-year 2026 sales guidance.

What Went Wrong for IONS?

Tryngolza, which is Ionis' first wholly owned marketed product, recently received label expansion in the severe hypertriglyceridemia (sHTG) indication, which has a significantly larger market opportunity than its initial label of familial chylomicronemia syndrome (FCS).

To improve patient access ahead of the expanded launch, Ionis had significantly reduced Tryngolza's annual wholesale acquisition cost (WAC) to $40,000, which came into effect in April 2026. Nevertheless, the drug generated net product sales of just $9 million in the third quarter of 2026, missing the Zacks Consensus Estimate of $23.1 million.

Management attributed the underperformance to a more gradual-than-anticipated launch ramp, as physicians take time to adopt the new treatment and reimbursement coverage gradually expands. Reflecting these headwinds, Ionis slashed its full-year 2026 Tryngolza sales guidance from its earlier projection of $100-$110 million to approximately $50 million, representing a reduction of around 50-55%. The sharp reduction reflects concerns about the pace of the drug’s commercialization.

Wainua royalties also disappointed investors. The AstraZeneca (AZN - Free Report) -partnered treatment generated $7 million in royalties during the quarter, significantly below the average analyst estimate of $17.7 million. Wainua had previously suffered a major clinical setback in July 2026, when a late-stage study failed to meet its primary endpoint in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). The failure has weakened prospects for expanding the drug into this larger market beyond its currently approved indication of polyneuropathy caused by hereditary transthyretin amyloidosis (ATTRv-PN).

These setbacks also have implications for Ionis' financial outlook. Though the company’s overall 2026 revenue guidance remains unchanged at $875-$900 million, management pushed back its target for sustained positive cash flow by one year to 2029. The revised timeline reflects the slower Tryngolza launch as well as setbacks in partnered late-stage clinical programs.

On the positive side, Ionis' wholly owned hereditary angioedema (HAE) drug Dawnzera continued to perform well. The drug generated third-quarter product sales of $37 million, increasing approximately 40% sequentially. This momentum supported management's decision to maintain the drug’s full-year 2026 sales guidance of $110-$120 million.

Competition Adds to Ionis’ Concerns

Tryngolza could face increased competition from Arrowhead Pharmaceuticals, which markets Redemplo, approved for FCS indication in November 2025. Arrowhead also recently posted positive late-stage results evaluating the drug in the sHTG indication, with plans for a regulatory filing before 2026-end. If approved, Redemplo could emerge as a direct competitor to Tryngolza in the broader sHTG market.

Meanwhile, Wainua operates in an increasingly competitive transthyretin amyloidosis market. A major competitor is Alnylam Pharmaceuticals' (ALNY - Free Report) Amvuttra, which is approved for both ATTRv-PN and ATTR-CM.

IONS Price Performance, Valuation & Estimates

Shares of Ionis have plunged more than 64% year to date, underperforming the industry’s break-even growth.

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Image Source: Zacks Investment Research

From a valuation standpoint, the company is currently trading at a premium to the industry. Based on the price-to-sales (P/S) ratio, the stock trades at 3.67 times forward 12-month sales, higher than the industry average of 2.10 times.

Zacks Investment Research
Image Source: Zacks Investment Research

Estimates for Ionis’ 2026 loss have remained consistent at $2.66 per share in the past 30 days. During the same time frame, those for 2027 have also remained constant at 98 cents.

Zacks Investment Research
Image Source: Zacks Investment Research

Ionis currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

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