• If you are wondering whether Ionis Pharmaceuticals' share price still reflects good value after a strong run, this article walks through what the current market price might be implying.
• The stock most recently closed at US$85.45, with returns of 5.0% over 7 days, 6.4% over 30 days, 7.3% year to date, 168.3% over 1 year, 138.0% over 3 years and 54.5% over 5 years, which naturally raises questions about future risk and reward.
• Recent news flow around Ionis has continued to focus on its role in the pharmaceuticals and biotech space and ongoing interest in its drug pipeline, which helps explain why investors are closely watching the share price. Broader coverage of the sector has also kept attention on how market participants are pricing companies with similar profiles to Ionis.
• On our valuation checks, Ionis scores 2 out of 6, and next we will look at how different valuation approaches interpret that score, before finishing with a way to look at valuation that goes beyond any single model.

Ionis Pharmaceuticals scores just 2/6 on our valuation checks. See what other red flags we found in the full valuation breakdown.

Approach 1: Ionis Pharmaceuticals Discounted Cash Flow (DCF) Analysis

A Discounted Cash Flow model estimates what a business might be worth by projecting its future cash flows and then discounting those back to today using a required rate of return. It is essentially asking what all those future dollars are worth in present day terms.

For Ionis Pharmaceuticals, the model used is a 2 Stage Free Cash Flow to Equity approach. The latest twelve month free cash flow is a loss of $294.8 million, and analyst based projections show free cash flow remaining negative in 2026 and 2027, then turning positive and reaching $851.3 million by 2030. Beyond the explicit analyst window, Simply Wall St extrapolates additional years of free cash flow using its own growth assumptions.

Pulling all of those projected cash flows together and discounting them back to today gives an estimated intrinsic value of about $268.94 per share in dollar terms. Compared with the recent share price of $85.45, the DCF output suggests the stock is around 68.2% undervalued based on these assumptions and forecasts.

Result: UNDERVALUED

Our Discounted Cash Flow (DCF) analysis suggests Ionis Pharmaceuticals is undervalued by 68.2%. Track this in your watchlist or portfolio, or discover 51 more high quality undervalued stocks.

Approach 2: Ionis Pharmaceuticals Price vs Sales

A price to sales, or P/S, ratio is often used for companies that are not yet consistently profitable but are generating revenue, because it compares what you pay for each dollar of sales rather than each dollar of earnings.

Higher growth expectations and lower perceived risk usually justify a higher P/S multiple, while slower growth and higher risk tend to support a lower, more conservative range. So what counts as a “normal” or “fair” P/S is very context dependent.

Ionis Pharmaceuticals currently trades on a P/S ratio of about 14.31x. That is above the Biotechs industry average of 11.89x and the peer group average of 4.87x, which suggests the market is assigning a richer valuation to its revenue than to many sector peers.

Simply Wall St’s Fair Ratio for Ionis, at 5.23x, is a proprietary estimate of what the P/S might be given factors such as earnings growth expectations, industry, profit margins, market capitalization and key risks. This tailored number can be more informative than a simple comparison with peers or the sector because it adjusts for company specific characteristics rather than treating all firms as alike.

Comparing the Fair Ratio of 5.23x with the current P/S of 14.31x indicates the shares screen as overvalued on this measure.

Result: OVERVALUED

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Upgrade Your Decision Making: Choose your Ionis Pharmaceuticals Narrative

Earlier we mentioned that there is an even better way to understand valuation. On Simply Wall St you can use Narratives, where you write the story you believe about Ionis Pharmaceuticals and connect it directly to your own forecasts for revenue, earnings and margins. These then link through to a Fair Value you can compare with the current share price to help decide whether to buy, hold or sell. This is all available within an easy Community page tool that updates automatically as new news or earnings arrive. One investor might build a bullish Ionis view around a Fair Value near US$116.76, while another might lean on a more cautious Fair Value close to US$43, and both can clearly see how their different assumptions lead to different price targets.

For Ionis Pharmaceuticals however we will make it really easy for you with previews of two leading Ionis Pharmaceuticals Narratives:

Fair Value: US$116.76 per share

Implied discount to this Fair Value: about 26.8% compared with the recent price of US$85.45

Revenue growth assumption: 34.23% per year

• Argues that late stage RNA programs and the antisense platform can support stronger future profitability, with several potential blockbuster launches across neurological, cardiovascular and rare disease areas.
• Assumes revenues reach about US$2.0b and earnings of US$373.9m by around 2028, with profit margins moving from a loss today to 25.29% and the shares trading on a future P/E of 41.46x.
• Highlights both upside and risks, including pricing pressure, regulatory outcomes, competition from gene editing and partnership dependence, and encourages you to test whether the bullish analyst assumptions fit your own expectations.

Fair Value: US$43.00 per share

Implied premium to this Fair Value: about 98.7% compared with the recent price of US$85.45

Revenue growth assumption: 3.04% per year

• Focuses on pricing pressure as Ionis shifts from high priced orphan indications to broader populations, with tighter payer and regulatory scrutiny potentially limiting revenue and margin expansion.
• Builds in only modest revenue growth and assumes margins eventually move toward the US Biotechs industry average of about 16.25%, which supports a Fair Value of US$43.00 using a future P/E of 51.13x.
• Flags execution risk around R&D spend, competition and partnership reliance, while acknowledging that stronger than expected commercial traction or pipeline delivery could challenge this more cautious view.

If you want to go beyond these short previews and see how other investors are framing upside and downside, Curious how numbers become stories that shape markets? Explore Community Narratives can help you compare different storylines with the same underlying data.

Do you think there's more to the story for Ionis Pharmaceuticals? Head over to our Community to see what others are saying!

This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.