Biogen (NASDAQ: BIIB) revenue climbs 11% but deal charges push it to a GAAP loss

What happened

Biogen Inc. (NASDAQ: BIIB) reported third-quarter 2026 revenue of $2.8 billion, up 11% from a year earlier, but swung to a GAAP loss. The company blames the loss mainly on deal charges. It still raised the floor of its 2026 earnings guidance.

GAAP diluted EPS was $(0.14), against $3.17 in the third quarter of 2025. The charges include $284 million of acquired in-process R&D, upfront and milestone expense, mostly for the acquisition of RayThera Inc. A year earlier the figure was $2 million. Net loss attributable to Biogen was $20.6 million, compared with net income of $466.5 million.

Non-GAAP diluted EPS was $2.62, down from $4.81. That measure still includes the same acquired R&D expense. For 2026, Biogen now expects non-GAAP diluted EPS of $12.20 to $13.00, up from $12.00 to $13.00. It cited ongoing business strength and favorable dilution from the Apellis acquisition.

Key numbers

Metric	Latest	Change	Source
Total revenue	$2.80 billion	from $2.53 billion, +10.6%	SEC 8-K, Q3 2026 press release
GAAP diluted EPS	$(0.14)	from $3.17, -104%	SEC 8-K, Q3 2026 press release
Non-GAAP diluted EPS	$2.62	from $4.81, -46%	SEC 8-K, Q3 2026 press release
Growth Portfolio revenue	$1.26 billion	+49%	SEC 8-K, Q3 2026 press release
Acquired IPR&D, upfront and milestone expense	$284 million	from $2 million	SEC 8-K, Q3 2026 press release
Free cash flow	$600.4 million	from $1.23 billion, -51.0%	Calculated from SEC 8-K

Read more: Biogen (BIIB) company research

Where the growth came from

The Growth Portfolio brought in $1.26 billion, up 49% and 63% of Core Pharmaceutical revenue. It includes the first full quarter of products acquired with Apellis, a deal that closed in May 2026. CEO Christopher A. Viehbacher said the results show Biogen "has returned to growth."

Syfovre sales were $191 million, up 27%, and Empaveli grew 92%. Prior-period figures for both come from Apellis' own third-quarter 2025 10-Q.

Established products also gained. Spinraza sold $461 million, up 23%. Biogen says conversion to a high-dose regimen continues to beat its expectations in all launched markets.

Skyclarys rose 34% to $178 million on U.S. and international demand and favorable U.S. inventory dynamics. Eisai recorded global Leqembi in-market sales of $202 million, up 67%.

Mature lines shrank. Multiple sclerosis revenue fell 13% to $919 million. Vumerity dropped 11% to $192 million, which Biogen says was hurt mainly by U.S. formulary dynamics. Biosimilars revenue fell 16% to $166 million.

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How much of the gain was acquired

Total revenue rose $269.4 million from the year-earlier quarter. Specialized immunology, which holds only Syfovre and Empaveli, brought in $242.8 million. By OptimistFi's calculation, that is 90.1% of the increase. Everything else combined added $26.6 million.

Rare disease revenue rose 27% and the rest of the Growth Portfolio gained. The small remainder reflects the multiple sclerosis and biosimilars declines offsetting those gains.

What pushed GAAP into a loss

GAAP R&D expense rose to $574 million from $436 million. Biogen cites higher clinical trial spending on felzartamab, salanersen and litifilimab, Apellis operating expenses, and less R&D funding from Royalty Pharma.

GAAP SG&A rose to $752 million from $595 million. Biogen points to Apellis operations and higher spending on product launches.

Cost of sales carried $194.8 million of amortization from the fair-value step-up of acquired inventory, tied to the Reata and Apellis acquisitions. That was up from $60.0 million. Restructuring charges were $66.5 million, up from $7.4 million.

The GAAP effective tax rate was negative 128.5%. Biogen blames mainly the non-deductible acquired R&D charge on the RayThera stock acquisition. The non-GAAP rate was 20.0%.

Why it matters

OptimistFi has argued that Biogen's value depends on new therapies growing fast enough to offset pressure on mature products. This quarter fits that view. Growth Portfolio revenue rose 49% while multiple sclerosis revenue fell 13%. The report strengthens the case, though most of the lift was bought rather than built.

Cash generation stayed positive but weakened. Free cash flow was $600.4 million, down 51.0% from $1.23 billion in the third quarter of 2025. Operating cash flow was about $641 million.

Cash and cash equivalents were $1.3 billion at Sept. 30, against $3.01 billion at Dec. 31, 2025. Net debt was $6.4 billion.

Biogen expects full-year revenue to rise by a mid-single digit percentage, driven by the Growth Portfolio. It expects combined non-GAAP R&D and SG&A expense of about $4.95 billion. The guidance assumes $3.20 per share of acquired R&D charges, up from $3.00 in the July guidance.

The caveats are plain. Guidance leaves out other future acquired R&D charges, acquisitions, pending and future litigation and healthcare reform. Biogen says these are hard to predict.

What's next

Biogen expects top-line data from the TOPAZ-1 and TOPAZ-2 Phase 3 studies of litifilimab in SLE in the first half of December 2026. Positive results would add to the pipeline needed to offset the multiple sclerosis decline. A miss would leave growth resting on acquired products.

Further Phase 3 readouts are expected for litifilimab in CLE and felzartamab in antibody mediated rejection in the first half of 2027. Zorevunersen in Dravet syndrome is expected in the third quarter of 2027.

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