Biogen Inc.

BIIB · NASDAQ · USD

Can the growth products and the newly acquired Apellis medicines offset multiple sclerosis erosion before late-stage readouts start adding revenue?

Last 4 earnings calls · through Q2 FY2026

Bull case

  • Growth products overtake legacy MS

    The bull case is that the newer medicines now bring in more revenue than the multiple sclerosis franchise, so the top line can grow while the old drugs shrink.

  • Apellis adds marketed medicines

    Buying Apellis adds two medicines that are already being sold and that management expects to keep growing faster than the rest of the portfolio.

  • High-dose SPINRAZA conversion

    Converting patients to high-dose SPINRAZA is running ahead of expectations and is winning some patients back from the oral competitor.

  • Late-stage readouts in untreated areas

    Several late-stage study results land within the next year in areas where there is no approved treatment, so any success opens a new market.

Bear case

  • Multiple sclerosis base erodes

    The bear case is that generic fumarates and a TYSABRI biosimilar are shrinking the multiple sclerosis base faster than the new products replace it.

  • Debt taken on for Apellis

    The Apellis purchase was paid for largely with new borrowing, so a much larger debt load and its interest cost now sit against earnings.

  • Binary late-stage trial results

    A return to growth rests on trial results that are years from becoming sales, and a miss would leave a hole the current portfolio cannot fill.

Bull and bear points

Growth & Execution

In short: Growth products now outsell the legacy MS business, but the MS decline still pulls total revenue down.

Bull · 2

  • Guidance moved from a revenue decline to growth

    In February management guided 2026 revenue to a mid-single-digit decline; in July it guided to a mid-single-digit increase, citing growth products and Apellis.

    Tone shiftQ4 FY2025 → Q2 FY2026

  • SPINRAZA shifts from flat to growing

    A year ago management guided SPINRAZA to roughly flat revenue; now it says high-dose conversion is beating the original launch, and SPINRAZA revenue rose 2.3% to $402 million.

    Tone shiftQ3 FY2025 → Q2 FY2026
Bear · 2

  • MS product revenue fell 13% as fumarate generics spread

    Multiple sclerosis products brought in $963 million in the quarter, down 13%, and management guides the non-VUMERITY MS line to a mid-teens decline for the year.

    Q4 FY2025 call

  • Growth now hinges on late-stage readouts

    Five registrational study readouts are due within about a year, and the launches they enable are the main lever management has to offset MS erosion.

    Q2 FY2026 call

Profitability & Financial Strength

In short: Free cash flow remains strong, but margins fell sharply after the Apellis deal and acquisition charges.

Bull · 2

  • Free cash flow covers investment and debt service

    The business generated $2.7 billion of free cash flow over the last twelve months, about 27% of revenue, which funds launch spending and debt repayment.

    Filed financials

  • Apellis deal expected to add to earnings

    Management expects at least $250 million of run-rate cost synergies from Apellis by the end of 2027 and says the deal turns accretive to earnings in 2027.

    Q2 FY2026 call
Bear · 1

  • Net debt nearly doubled to fund Apellis

    Net debt stands at $6.8 billion against $3.5 billion a year earlier, and financing the deal costs about $120 million to $130 million a year in interest and lost income.

    Q2 FY2026 call

Market Position

In short: LEQEMBI leads the anti-amyloid market, but MS generics and biosimilars keep eroding the base business.

Bull · 2

  • Home dosing sets LEQEMBI apart from its rival

    Approval of subcutaneous LEQEMBI for both starting and maintenance dosing removes the infusion visits that keep some patients and caregivers from starting treatment.

    Q2 FY2026 call

  • TYSABRI holds up against a biosimilar

    TYSABRI revenue was $451 million, down less than one percent, as growing use of the subcutaneous form offset biosimilar competition in Europe.

    Filed financials
Bear · 2

  • US pricing rules reshape what Biogen collects

    Medicare drug coverage changes and potential negotiated prices under the Inflation Reduction Act affect how much Biogen keeps per prescription across the portfolio.

    10-K, filed 2026-02-06

  • Crowded lupus field raises the bar

    Litifilimab enters systemic lupus against roughly 55 other ongoing trials, and earlier lupus launches have struggled to win wide use among rheumatologists.

    Q4 FY2025 call