Why the Alnylam Sell-Off Looks Overdone — and What Investors Are Missing

Alnylam Pharmaceuticals (ALNY +0.67%) looks like an investor’s nightmare at first glance. The drugmaker’s shares have lost more than half their value over the past 12 months. The biotech stock is down more than 20% over the past four weeks.

Some Alnylam shareholders could be sorely tempted to throw in the towel. However, I think there’s a strong case that the sell-off is way overdone. And I believe that many investors are missing a bigger story with Alnylam.

Why Alnylam’s stock has been a dumpster fire

Alnylam gave what appears, in retrospect, to be an early warning of a significant problem in its 2025 fourth-quarter results, announced in February 2026. Sales for the company’s transthyretin-mediated (ATTR) amyloidosis therapy, Amvuttra, were lower than Wall Street expected.

But the full extent of the issue became apparent when Alnylam released its 2026 second-quarter results on July 30. Amvuttra’s sales were again below expectations. The big story, though, was that Alnylam lowered its full-year sales guidance for its TTR products (which include Amvuttra and Onpattro) by $200 million.

Today’s Change

(0.67%) $1.53

Current Price

$228.65

Key Data Points

Market Cap

$31BMarket cap calculated using publicly traded shares outstanding only. Does not include unlisted, private, or dual-class non-traded shares. Implied market cap may vary.

Day’s Range

$220.23 – $228.98

52wk Range

$197.81 – $495.55

Volume

1.5M

Avg Vol

1.6M

Gross Margin

79.65%

Alnylam CEO Yvonne Greenstreet said that the reduced guidance reflected “a better understanding with hindsight” of Amvuttra’s launch in the transthyretin amyloid cardiomyopathy (ATTR-CM) market. She noted that the initial exceptionally strong sales growth in the ATTR-CM indication last year “benefited significantly from pent-up demand for a new therapy that has since normalized.”

Meanwhile, rival BridgeBio‘s (BBIO -1.66%) ATTR-CM drug, Attruby, is gaining momentum. Attruby’s sales more than tripled year over year in Q2 to $222.4 million — better than analysts expected. This growth makes Alnylam’s disappointment with Amvuttra sting even more.

To make matters worse, a cloud hovers over Alnylam’s next-generation ATTR therapy, nucresiran, which is currently in late-stage clinical testing. AstraZeneca (AZN -0.50%) and Ionis Pharmaceuticals (IONS +2.45%) reported in July that their experimental ATTR-CM drug, eplontersen, failed to meet the primary endpoint in a Phase 3 study. This clinical setback raised questions about whether the chances of success for nucresiran are lower than anticipated.

The rest of the story

You might think that Amvuttra’s sales are struggling based on the market’s reaction to Alnylam’s Q2 update. However, that isn’t the case at all. Sales for the drug more than doubled year over year in Q2 to $1.01 billion. This marked the first quarter in which Amvuttra raked in more than $1 billion.

Sure, management overestimated how strong Amvuttra’s growth trajectory would be. But Alnylam should now be able to more accurately forecast sales for the blockbuster drug — and growth should remain robust. Importantly, Amvuttra remains the only therapy approved for the full spectrum of TTR amyloidosis.

I’m not worried about comparisons with BridgeBio’s Attruby, either. It makes sense that Attruby’s growth would be stronger at this point. The drug won its first U.S. Food and Drug Administration (FDA) approval in November 2024. Alnylam secured the first FDA approval for Amvuttra in more than two years earlier and added an ATTR-CM approval in March 2025.

As for the concerns about AstraZeneca’s and Ionis’ setback for eplontersen, I agree with Stifel (SF -0.07%) analyst Paul Matteis’ take that it’s “a huge positive” for Amvuttra. I don’t think that Eplontersen’s failure makes it more likely that nucresiran will flop, either. The two drugs use different mechanisms for silencing genes. If anything, Alnylam should be able to learn from any mistakes made with eplontersen’s clinical trial design.

Last but not least, Pfizer‘s (PFE -0.04%) Vyndaqel/Vyndamax (tafamidis) will no longer face a generic rival in the U.S. until mid-2031. This gives Alnylam and Amvuttra more runway for growth. Between this delay and eplontersen’s late-stage disappointment, the competitive landscape has shifted dramatically in Alnylam’s favor.

Alnylam’s future still looks bright.

I noticed one word repeated throughout Alnylam’s Q2 update: confidence. The company is confident about Amvuttra’s growth. It’s confidence about continued leadership in ATTR. It’s confident about nucresiran. Greenstreet said that she’s “more confident about our future outlook” than before. Management’s confidence extends to its goal of generating at least 25% compound annual growth in total revenue through 2030.

Sure, Alnylam faces risks. All stocks do. But many investors appear to be missing the fact that Alnylam’s future still looks bright.

Many are also overlooking Alnylam’s valuation. No, it isn’t a stock that would appeal to most value investors. However, Alnylam’s price-to-earnings-to-growth (PEG) ratio, which is based on analysts’ five-year earnings growth projections, is a super-low 0.41.

The recent sell-off is overdone, in my view. That creates a great buying opportunity for forward-looking investors.