Alnylam Pharmaceuticals Stock: 5 Straight Red Days, Down 14%
A biotech firm’s stock is on a multi-day slide, prompting a closer look at its high-growth profile against its premium valuation.
Alnylam Pharmaceuticals (ALNY) focuses on discovering, developing, and commercializing novel therapeutics based on ribonucleic acid interference. The market has put the stock on a downward path, as it has now moved lower for 5 consecutive trading days. The cumulative loss over this period is 13.7%, which has erased about $5.9 billion from the company’s market value.
The company’s pipeline of investigational RNAi therapeutics focuses on genetic medicines, cardio-metabolic diseases, hepatic infectious diseases, and central nervous system (CNS/ocular) diseases. Its marketed products include ONPATTRO (patisiran).
How The Streak Stacks Up Against The S&P 500
Here is how ALNY stock stacks up against the S&P 500 over the streak and the periods around it:
| Return Period | ALNY | S&P 500 |
|---|---|---|
| 1D | -0.8% | 0.4% |
| 5D (Current Streak) | -13.7% | 1.2% |
| 1M (21D) | -1.3% | 1.9% |
| 3M (63D) | -17.8% | 8.7% |
| YTD 2026 | -29.8% | 10.6% |
| 2025 | 69.0% | 16.4% |
| 2024 | 22.9% | 23.3% |
| 2023 | -19.5% | 24.2% |
What do the fundamentals say about this price action?
The evidence is mixed. Alnylam’s revenue over the last twelve months grew 82.6%, far outpacing the S&P 500 median revenue growth of 7.5%. Yet its operating margin of 17.5% is just below the S&P 500 median of 18.4%. The market is pricing the company at a significant premium, with a price-to-earnings multiple of 64.3, well above the median of 24.2.
This streak appears specific to the company. Over the same 5 trading days, the S&P 500 returned +1.2%, suggesting the move is mostly this stock’s own story. Such streaks are not unusual in the current market; 34 S&P 500 stocks are on losing streaks of 3 days or more.
A streak is a signal, not a command.
A multi-day move is information. It reflects a shift in momentum and draws attention to a stock, but it does not provide an instruction to buy or sell. The disciplined response is to use this moment to re-evaluate the relationship between the business and its price. The numbers show a company with very high growth being valued at a premium, and the recent slide forces an investor to decide if that trade-off remains sound.
If the drop has you weighing an entry, resist buying a falling price alone. Our Buy the Dip screen ranks the marked-down names where growth and cash generation still support a recovery.
Prefer the theme to this single name? A biotech ETF like IBB owns the whole group. It is still a concentrated bet on that one theme, though, which is exactly the gap the portfolio below closes.
Weakness In One Name Should Be Noise, Not News
For a diversified holder, a streak like this is a data point. For a concentrated one, it is a hole in the plan. The difference is never the stock; it is the portfolio built around it.
Building that portfolio is what the Trefis High Quality (HQ) Portfolio does: roughly 30 businesses with the cash generation and balance-sheet strength to absorb a bad month, selected and rebalanced by rules. It has a track record of outpacing a benchmark that combines all major indices – the S&P 500, S&P Mid-cap, and Russell 2000. Make the next streak, in either direction, someone else’s drama.