Alnylam Pharmaceuticals Stock: 5 Straight Red Days, Down 14%
Shares of Alnylam Pharmaceuticals (ALNY) have closed lower in each of the last 5 sessions, a cumulative decline of 14.2%. That erased about $4.8 billion from the company’s market value, which now stands at about $29.4 billion. The stock closed at $219.72 on Friday, October 2, 55.3% below its 52-week high of $491.22 and 6.9% above its low of $205.48.
ALNY Versus The S&P 500
Returns for ALNY and the S&P 500 over the streak and the periods around it, all ending Friday, October 2 and including dividends:
| Return Period | ALNY | S&P 500 |
|---|---|---|
| 1 Day | -5.0% | 0.7% |
| 5 Days (Current Streak) | -14.2% | -0.2% |
| 1 Month (21 Trading Days) | -17.8% | 0.8% |
| 3 Months (63 Trading Days) | -29.8% | 2.7% |
| Year To Date | -44.7% | 13.8% |
| 1 Year (252 Trading Days) | -52.3% | 16.4% |
A Stock-Specific Slide, Or A Market Move?
Over the same 5 trading days, the S&P 500 returned -0.2% including dividends, so the slide is mostly Alnylam Pharmaceuticals’ own story rather than the market’s. Over the past three months the stock is down 29.8%, a window that includes the streak; over the other 58 sessions of that window it was down 18.2%.
What The Numbers Say About The Slide
On the fundamentals, revenue grew 95.1% over the last twelve months, against a median of 8.1% for S&P 500 Health Care stocks; its operating margin is 20.8%, versus a median of 18.3%; and the stock trades at 36.3 times trailing earnings against a median of 28.3. The read is mixed.
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A Slide Like This Is Why Diversification Exists
Watching one stock fall day after day is the clearest lesson the market teaches about single-name risk. Whether this particular decline is an opportunity or a warning, the deeper point is the same: no one name should be able to do this to your portfolio.
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