BIIB Q2: Growth Portfolio Overtakes MS, Leqembi Hits $184M

Biogen (BIIB) reported second-quarter 2026 revenue of $2.74 billion on July 29, up 3% year over year, with the Growth Portfolio generating $1.06 billion in revenue, up 24% YoY. For the first time, the Growth Portfolio exceeded the Legacy MS portfolio, which brought in $767 million and continues to decline. Shares closed at $205.61, up 2.73%.

The numbers

• Ticker: BIIB
• Stock price: $205.61 (close July 29, 2026)
• Q2 revenue: $2.74 billion (+3% YoY)
• Non-GAAP diluted EPS: $3.60
• Growth Portfolio revenue: $1.06 billion (+24% YoY)
• Legacy MS revenue: $767 million
• Leqembi global in-market sales: $184 million (+15% YoY; US $97 million)
• Syfovre: $97.4 million (first full quarter post-Apellis close)
• EMPAVELI: $30.4 million
• Spinraza: $204.3 million (+37% YoY, driven by high-dose regimen demand)
• Skyclarys: $82.3 million
• Zurzuvae: $70.7 million

Growth Portfolio crosses the line

The Growth Portfolio includes Leqembi, Spinraza, Skyclarys, Zurzuvae, Qalsody, Syfovre, and EMPAVELI. The Legacy MS portfolio (Tecfidera, Vumerity, Avonex, Plegridy, Tysabri) generated $767 million this quarter, down from $963 million a year ago, as generic competition erodes Tecfidera and Vumerity sales.

Leqembi’s $184 million in global in-market sales slightly missed the $186 million consensus but grew 15% YoY. The Leqembi subcutaneous Iqlik approval in July 2026 enables at-home initiation dosing, supporting continued sequential growth. US in-market sales were $97 million. Leqembi’s primary known safety concern is ARIA (amyloid-related imaging abnormalities), which occurred in 12.6 percent of patients in the CLARITY AD trial and requires MRI monitoring during treatment.

The Apellis acquisition, closed May 14 for $5.6 billion, contributed Syfovre ($97.4 million) and EMPAVELI ($30.4 million) to Specialized Immunology. These products added $30 million in revenue recognized since the close date.

Pipeline signals

Three pipeline moves were announced alongside earnings:

1. BIIB091 (BTK inhibitor): Phase 2 FUSION data in relapsing-remitting MS achieved proof of concept. Biogen will explore next steps. BIIB091 is a reversible, non-covalent oral BTK inhibitor that suppresses B-cell activation. Unlike B-cell-depleting therapies, BTK inhibition reduces activation while preserving B-cell viability, avoiding infection risk from chronic depletion.

2. Ionis ALS option exercise: Biogen exercised its option for a worldwide exclusive license to an oligonucleotide targeting stathmin-2 pre-mRNA in broad ALS. Stathmin-2 loss, driven by TDP-43 pathology, is implicated in ALS neurodegeneration.

3. RayThera acquisition: Biogen agreed to acquire private immunology company RayThera for up to $1 billion (upfront plus milestones) on June 17. The lead candidate enters Phase 1 in Q3 2026.

What to watch

Five registrational readouts are expected over the next four quarters. The highest-impact catalysts:

• Litifilimab in cutaneous lupus erythematosus (Phase 3 AMETHYST, data expected 2027, FDA Breakthrough Therapy designation). A separate SLE Phase 3 trial has results expected between 2026 and 2027.
• Felzartamab in antibody-mediated rejection in kidney transplant (Phase 3 TRANSCEND, first readout 2027).
• Zorevunersen in Dravet syndrome (Phase 3 EMPEROR, data mid-2027, rolling NDA submission planned for H1 2027).

The near-term risk is Apellis dilution: the acquisition is expected to have a $0.85 EPS impact in 2026 before turning accretive in 2027. GAAP diluted EPS was just $0.66 this quarter, weighed down by acquisition costs and IPR&D charges. Biogen updated its 2026 outlook to mid-single-digit revenue growth, up from a prior decline projection.

The competitive risk for BIIB091 is real: Novartis’s remibrutinib and Roche’s fenebrutinib are also oral BTK inhibitors in Phase 3 for MS, ahead of BIIB091. Biogen will need to differentiate on efficacy or safety to justify advancing to Phase 3.

Biogen Q2 2026 press release | RayThera acquisition press release | Biogen diranersen CELIA tau analysis