Alnylam Shares Plunge 25% as TTR Guidance Tilts to Low End Despite Revenue Growth

Alnylam shares closed down 25.13% on Thursday after the drugmaker said TTR sales would land at the low end of guidance, overshadowing 52% product revenue growth.

Alnylam Pharmaceuticals reported third-quarter 2026 results on Thursday, Oct. 29, 2026. The quarter covered the three months ended Sept. 30, 2026.

Total revenues were $1.46 billion, up 17% from $1.25 billion a year earlier. Global net product revenues were $1.29 billion, up 52% from $851 million.

Total TTR revenues were $1.15 billion, up 59% from a year earlier. TTR is transthyretin, the protein targeted by the company's lead franchise.

AMVUTTRA sales were $1.13 billion, up 65% in the quarter. ONPATTRO sales were $19.6 million, down 50% as patients shifted products.

Total Rare revenues were $142.0 million, up 12% in the quarter. GIVLAARI sales were $89.5 million, up 21%, and OXLUMO sales were $52.5 million, down 1%.

Collaboration revenue was $71 million, down 80% from a year earlier. The prior year included a $300 million Roche milestone payment.

Royalty revenue was $95 million, more than double the year-earlier level. Product growth, not partner payments, drove the quarter.

Operating profit fell as costs rose

Reported income from operations was $345.8 million, down 6% from $368.0 million. Non-GAAP operating income was $424.9 million, down 11%.

Non-GAAP strips out stock-based compensation the company treats separately. Cost of goods sold was $361.8 million in the quarter.

Cost of goods sold equaled 28.0% of net product revenues. That compared with 23.2% a year earlier, the release said.

A tax benefit, not operations, lifted net income

Reported net income was $2.17 billion, against $292.7 million a year earlier. Reported profit was $16.19 a share basic and $15.72 a share diluted.

The jump came from an income-tax benefit of $1.87 billion. It reflected releasing valuation allowances on United States deferred tax assets.

A valuation allowance is a reserve against tax assets a company may not use. Releasing it lifts reported profit without adding cash sales.

Income before income taxes was $295.8 million, the statements showed. The $15.72 diluted figure is therefore tax-driven, not operating performance.

Cash, cash equivalents and marketable securities were $3.6 billion at Sept. 30, 2026. That compared with $2.9 billion at Dec. 31, 2025.

Guidance held, but TTR tilts low

Alnylam reiterated full-year 2026 guidance for total net product revenues. The range stays at $4.7 billion to $5.1 billion.

Total TTR guidance also stays at $4.2 billion to $4.5 billion. But management said TTR sales are expected at the low end of that range.

Stocktwits reported that chief executive Yvonne Greenstreet said the company is not yet satisfied with underlying demand growth. That was despite expanded sales-force efforts.

Increased physician engagement has not yet translated into increased demand growth, Stocktwits reported. Management cited the time needed to shift prescribing habits.

On access, a more restrictive UnitedHealth policy took effect Oct. 1. Stocktwits reported it could create some delays for new patients.

Shares closed down 25.13%

The guidance tilt, not the reported growth, is what investors punished. Shares closed at $174 on Thursday, Finnhub data showed.

That close was down 25.13% from the prior close of $232.40. The settled regular-session close is the single snapshot used here.

What remains unknown

What remains unknown is whether fourth-quarter demand converts faster. Management has not yet satisfied itself on underlying demand growth.

Also unknown is the full effect of the UnitedHealth policy on new starts. The company said 2027 guidance will wait until February results.

What to watch is fourth-quarter TTR sales against the low end. Investors will also check whether cost ratios ease from 28.0%.