Biogen (BIIB) 10-K risk factor changes: FY2016 vs FY2015

| • | constraints and additional pressures on product pricing or price increases, [removed: due to a number of factors,] including [added: those resulting from] governmental or regulatory requirements, increased competition, or changes [removed: in] [added: in, or implementation of,] reimbursement policies and practices of payors and other third parties; or |

| • | our limited marketing experience within the [removed: hemophilia treatment] [added: spinal muscular atrophy] market, which may impact our ability to develop relationships with the associated medical and scientific community; [removed: or] |

Our inability to maintain adequate coverage, or a reduction in pricing or reimbursement, could have an adverse effect on our business, revenues and results of [removed: operations,] [added: operations] and could cause a decline in our stock price.

| • | changes [removed: in] [added: in, and implementation of,] federal, state or foreign government regulations or private third-party payors' reimbursement policies; |

Thus, our inability to secure adequate prices in a particular country may not only limit the [removed: marketing of] [added: revenue from] our products within that country, but may also adversely affect our ability to obtain acceptable prices in other markets.

Our failure to maintain adequate coverage, pricing, or reimbursement for our products would have an adverse effect on our business, revenues and results of [removed: operation,] [added: operations,] could curtail or eliminate our ability to adequately fund research and development programs for the discovery and commercialization of new [removed: products,] [added: products] and could cause a decline in our stock price.

[removed: Drug] [added: We expect drug] pricing and other health care costs [added: to] continue to be subject to intense political and societal pressures [removed: which we anticipate will continue and escalate] on a global basis.

For example, provisions of the [removed: Patient Protection and Affordable Care Act (PPACA)] [added: PPACA] have resulted in changes in the way health care is paid for by both governmental and private insurers, including increased rebates owed by manufacturers under the Medicaid Drug Rebate Program, annual fees and taxes on manufacturers of certain branded prescription drugs, the requirement that manufacturers participate in a discount program for certain outpatient drugs under Medicare Part D and the expansion of the number of hospitals eligible for discounts under Section 340B of the Public Health Service Act.

These measures vary by country and may include, among other things, patient access restrictions, suspensions on price increases, prospective and possibly retroactive price reductions and other recoupments and increased mandatory discounts or rebates, recoveries of past price [removed: increases,] [added: increases] and greater importation of drugs from lower-cost countries to higher-cost countries.

Discovery of safety issues with our products could create product liability and could cause additional regulatory scrutiny and requirements for additional labeling or safety monitoring, withdrawal of products from the [removed: market,] [added: market] and the imposition of fines or criminal penalties.

The degree of patent protection that will be afforded to our products and processes in the U.S. and in other important markets remains uncertain and is dependent upon the scope of protection decided upon by the patent offices, [removed: courts] [added: courts, administrative bodies] and lawmakers in these countries.

We may also face challenges to our patent and regulatory protections covering our products by [added: third parties, including] manufacturers of generics and biosimilars that may choose to launch or attempt to launch their products before the expiration of our patent or regulatory exclusivity.

Litigation, interference, oppositions, inter partes [removed: reviews] [added: reviews, administrative challenges] or other similar types of proceedings are unpredictable and may be protracted, expensive and distracting to management.

Clinical trials may indicate that our product candidates lack efficacy, have harmful side effects, result in unexpected adverse [removed: events,] [added: events] or raise other concerns that may significantly reduce the likelihood of regulatory approval.

This may result in [added: terminated programs,] significant restrictions on use and safety warnings in an approved label, adverse placement within the treatment paradigm, or significant reduction in the commercial potential of the product candidate.

These factors include protocol design, regulatory and institutional review board approval, patient enrollment [removed: rates,] [added: rates] and compliance with extensive current Good Clinical Practices.

If we or our third-party clinical trial providers or third-party contract research [removed: organizations, or CROs,] [added: organizations (CROs)] do not successfully carry out these clinical activities, our clinical trials or the potential regulatory approval of a product candidate may be delayed or be unsuccessful.

One CRO has responsibility for [removed: substantially all] [added: a substantial portion] of our clinical trial related activities and reporting.

Successful preclinical work or early stage clinical trials [removed: does] [added: do] not ensure success in later stage trials, regulatory approval or commercial viability of a product.

| • | Global Bulk Supply Risks. We rely on our [added: principal] manufacturing facilities [removed: in Cambridge, Massachusetts, RTP, North Carolina and Hillerød, Denmark] for the production of drug substance for our large molecule products and product candidates. Our global bulk supply of these products and product candidates depends on the uninterrupted and efficient operation of these facilities, which could be adversely affected by equipment failures, labor shortages, natural disasters, power failures and numerous other factors. |

| • | Risks Relating to Compliance with cGMP. We and our third-party providers are generally required to maintain compliance with cGMP and other stringent requirements and are subject to inspections by the FDA and comparable agencies in other jurisdictions to confirm such compliance. Any delay, interruption or other issues that arise in the manufacture, fill-finish, [removed: packaging,] [added: packaging] or storage of our products as a result of a failure of our facilities or the facilities or operations of third parties to pass any regulatory agency inspection could significantly impair our ability to develop and commercialize our products. Significant noncompliance could also result in the imposition of monetary penalties or other civil or criminal sanctions and damage our reputation. |

Any adverse developments affecting our manufacturing operations or the operations of our third-party suppliers and manufacturers may result in shipment delays, inventory shortages, lot failures, product withdrawals or [removed: recalls,] [added: recalls] or other interruptions in the commercial supply of our products.

We rely on a number of significant collaborative relationships for revenue, and the development, regulatory approval, [removed: commercialization,] [added: commercialization] and marketing of certain of our products and product candidates.

Reliance on collaborative [added: and other third-party] relationships subjects us to a number of risks, including:

| • | we may be unable to control the resources our [removed: collaborator devotes] [added: collaborators or third parties devote] to our programs or products; |

| • | disputes may arise [added: under the agreement, including] with respect to [added: the achievement and payment of milestones or] ownership of rights to technology developed with our [removed: collaborator,] [added: collaborators or other third parties,] and the underlying contract with our [removed: collaborator] [added: collaborators or other third parties] may fail to provide significant protection or may fail to be effectively enforced if the [removed: collaborator fails] [added: collaborators or third parties fail] to perform; |

| • | [removed: our collaborator’s] [added: the] interests [added: of our collaborators or third parties] may not always be aligned with our [removed: interests and a collaborator] [added: interests, such parties] may not pursue regulatory approvals or market a product in the same manner or to the same extent that we would, which could adversely affect our revenues; |

| • | [added: third-party relationships and] collaborations often require the parties to cooperate, and failure to do so effectively could adversely affect product [removed: sales by our collaborator] [added: sales,] or the clinical development or regulatory approvals of products under joint control or could result in termination of the research, development or commercialization of product candidates or result in litigation or arbitration; and |

| • | any failure on the part of our [removed: collaborator] [added: collaborators or other third parties] to comply with applicable laws and regulatory requirements in the marketing, sale and maintenance of the [removed: market] [added: marketing] authorization of our products or to fulfill any responsibilities our [removed: collaborator] [added: collaborators or other third parties] may have to protect and enforce any intellectual property rights underlying our products could have an adverse effect on our revenues as well as involve us in possible legal proceedings. |

Our business may be adversely affected if we do not [removed: manage our current growth and do not] successfully execute our growth initiatives.

We anticipate growth through internal development projects, commercial [removed: initiatives,] [added: initiatives] and external opportunities, which may include the acquisition, partnering and in-licensing of products, technologies and companies or the entry into strategic alliances and collaborations.

The availability of high [removed: quality] [added: quality, cost-effective] development opportunities is limited and competitive, and we are not certain that we will be able to identify candidates that we and our shareholders consider suitable or complete transactions on terms that are acceptable to us and our shareholders.

Our [removed: growth] [added: success] is [removed: also] dependent upon our ability to attract and retain qualified [removed: scientific, information technology, manufacturing, sales and marketing and executive personnel and to develop and maintain relationships with qualified clinical researchers] [added: management] and key [removed: distributors] [added: personnel] in a highly competitive environment.

We may face difficulty in attracting and retaining key talent for a number of reasons, such as [added: management changes,] the underperformance or discontinuation of one or more late stage programs or recruitment by competitors.

If we do not successfully manage our [removed: current] growth [removed: and do not successfully execute our growth] initiatives, then our business and financial results may be adversely affected and we may incur asset impairment or restructuring charges.

Cyber-attacks are increasing in their frequency, sophistication and [removed: intensity.][added: intensity, and are becoming increasingly difficult to detect.]

While we continue to build and improve our systems and infrastructure and believe we have taken appropriate security measures to reduce these risks to our data and information technology systems, there can be no assurance that our efforts will prevent breakdowns or breaches in our systems that could adversely affect our business and [removed: operations.][added: operations and/or result in the loss of critical or sensitive information, which could result in financial, legal, business or reputational harm to us.]

In addition, [removed: we along with many other pharmaceutical and biotechnology] [added: health care] companies [added: such as ours] have been the target of lawsuits and investigations alleging violations of government regulation, including claims asserting submission of incorrect pricing information, impermissible off-label promotion of pharmaceutical products, payments intended to influence the referral of health care business, submission of false claims for government reimbursement, antitrust [removed: violations,] [added: violations] or violations related to environmental matters.

[removed: These risks] [added: Risks relating to compliance with laws and regulations] may be heightened as we continue to expand our global operations and enter new therapeutic areas with different patient populations, which may have [added: different] product distribution [removed: methods differing] [added: methods, marketing programs or patient assistance programs] from those we currently [removed: utilize.][added: utilize or support.]

| • | new laws, regulations or judicial decisions, or new interpretations of existing laws, regulations or decisions, related to health care availability, pricing or marketing practices, compliance with wage and hour laws and other employment practices, method of delivery, payment for health care products and services, compliance with health information and data privacy and security laws and regulations, tracking and reporting payments and other transfers of value made to physicians and teaching hospitals, extensive anti-bribery and anti-corruption prohibitions, product serialization and labeling [removed: requirements,] [added: requirements] and used product take-back requirements; |

Our current revenues depend upon continued sales of our principal products, and, unless we develop or acquire rights to new products and technologies, we may be substantially dependent on sales from our principal products for many years.

Further, following the completion of the spin-off of our hemophilia business, our revenues will be further reliant and concentrated on sales of our MS products in an increasingly competitive market, and revenue from sales of our product for spinal muscular atrophy.

SPINRAZA was recently approved by the FDA, and is in the early stages of commercial launch.

In addition to risks associated with new product launches and the other factors described in these “Risk Factors”, our ability to successfully commercialize SPINRAZA may be adversely affected due to:

| • | the lack of readiness of healthcare providers to treat patients with spinal muscular atrophy; |

| • | the effectiveness of our commercial strategy for marketing SPINRAZA; and |

| • | our ability to maintain a positive reputation among patients, healthcare providers and others in the spinal muscular atrophy community, which may be impacted by pricing and reimbursement decisions relating to SPINRAZA. |

In 2017, we may face uncertainties as a result of likely federal and administrative efforts to repeal, substantially modify or invalidate some or all of the provisions of the PPACA.

There is no assurance that the PPACA, as currently enacted or as amended in the future, will not adversely affect our business and financial results, and we cannot predict how future federal or state legislative or administrative changes relating to healthcare reform will affect our business.

Management and key personnel changes may disrupt our operations, and we may have difficulty retaining key personnel or attracting and retaining qualified replacements on a timely basis for management and other key personnel who may leave the Company.

We have experienced changes in management and other key personnel in critical functions across our organization, including our chief executive officer, and heads of research and development and pharmaceutical operations and technology.

Changes in management and other key personnel have the potential to disrupt our business, and any such disruption could adversely affect our operations, programs, growth, financial condition and results of operations.

Further, new members of management may have different perspectives on programs and opportunities for our business, which may cause us to focus on new business opportunities or reduce or change emphasis on our existing business programs.

Qualified individuals are in high demand, and we may incur significant costs to attract them, particularly at the executive level.

We cannot assure that we will be able to hire or retain the personnel necessary for our operations or that the loss of any such personnel will not have a material impact on our financial condition and results of operations.

We also outsource to third parties certain aspects of our regulatory affairs and clinical development relating to our products and product candidates.

While we believe we have a number of promising programs in our pipeline, failure of internal development projects to advance or difficulties in executing on our commercial initiatives could impact our current and future growth, resulting in additional reliance on external development opportunities for growth.

We may incur operational difficulties or be exposed to claims and liabilities as a result of the separation and distribution of Bioverativ.

On February 1, 2017, we distributed all of the then outstanding shares of Bioverativ common stock to Biogen stockholders in connection with the separation of our hemophilia business.

In connection with the distribution, we entered into a separation and distribution agreement and various other agreements (including a transition services agreement, a tax matters agreement, a manufacturing and supply agreement, an employee matters agreement, an intellectual property matters agreement and certain other commercial agreements).

These agreements govern the separation and distribution and the relationship between the two companies going forward, including with respect to potential tax-related losses associated with the separation and distribution.

They also provide for the performance of services by each company for the benefit of the other for a period of time (including under the manufacturing and supply agreement pursuant to which we will manufacture and supply certain products and materials to Bioverativ).

There could be significant liability if the separation and distribution is determined to be a taxable transaction.

Bioverativ has agreed to indemnify us for certain potential liabilities that may arise, but we cannot guarantee that Bioverativ will be able to satisfy its indemnification obligations.

The separation and distribution agreement provides for indemnification obligations designed to make Bioverativ financially responsible for many liabilities that may exist relating to its business activities, whether incurred prior to or after the distribution, including any pending or future litigation.

It is possible that a court would disregard the allocation agreed to between us and Bioverativ and require us to assume responsibility for obligations allocated to Bioverativ.

Third parties could also seek to hold us responsible for any of these liabilities or obligations, and the indemnity rights we have under the separation and distribution agreement may not be sufficient to fully cover all of these liabilities and obligations.

Even if we are successful in obtaining indemnification, we may have to bear costs temporarily.

In addition, our indemnity obligations to Bioverativ may be significant.

These risks could negatively affect our business, financial condition or results of operations.

The separation of Bioverativ continues to involve a number of risks, including, among other things, the indemnification risks described above and the potential that management’s and our employees’ attention will be significantly diverted by the provision of transitional services.

Certain of the agreements described above provide for the performance of services by each company for the benefit of the other for a period of time.

If Bioverativ is unable to satisfy its obligations under these agreements, including its indemnification obligations, we could incur losses.

These arrangements could also lead to disputes over rights to certain shared property and over the allocation of costs and revenues for products and operations.

Our inability to effectively manage the separation activities and related events could adversely affect our business, financial condition or results of operations.

We may not achieve some or all of the expected benefits of the separation and distribution, and such events may adversely affect our business.

We may not be able to achieve the full strategic and financial benefits expected to result from the separation and distribution, or such benefits may be delayed or not occur at all.

If we fail to achieve some or all of the expected benefits of the separation, or if such benefits are delayed, our business, financial condition, results of operations and the value of our stock could be adversely impacted.

They are often carried out by motivated, well-resourced, skilled and persistent actors including nation states, organized crime groups and "hacktivists." Cyber-attacks could include the deployment of harmful malware and key loggers, a denial-of-service attack, a malicious website, the use of social engineering and other means to affect the confidentiality, integrity and availability of our technology systems and data.

Our key business partners face similar risks and any security breach of their systems could adversely affect our security posture.

Our current revenues depend upon continued sales of our principal products.

We may be substantially dependent on sales from our principal products for many years, including an increasing reliance on sales and growth of TECFIDERA as we further expand into additional markets.

Similarly, the hemophilia treatment market is highly competitive, with current treatments marketed by companies that have substantially greater financial resources and marketing expertise.

Our ability to successfully compete in the hemophilia market and gain share in this market may be adversely affected due to a number of reasons, including:

| • | difficulty in penetrating this market if our therapies are not regarded as offering significant benefits over current treatments; |

| • | the introduction by other companies of longer-lasting or more efficacious, safer, less expensive or more convenient treatments than our therapies; |

| • | if one of several companies that are working to develop additional treatments for hemophilia obtains marketing approval of its treatment in the E.U. before we do, our application for ALPROLIX with the EMA could be barred under operation of the EMA’s orphan medicinal product regulation. |

In addition, under the PPACA, as states implement their health care marketplaces or operate under the federal exchange, the impact on drug manufacturers, including us, will depend in part on the formulary and benefit design decisions made by insurance sponsors or plans participating in these programs.

It is possible that we may need to provide discounts or rebates to such plans in order to maintain favorable formulary access for our products for this patient population, which could have an adverse impact on our sales and results of operations.

We may fail to achieve the expected financial and operating benefits of our corporate restructuring and the restructuring may harm our business and financial results.

We face significant risks associated with our corporate restructuring actions that may impair our ability to achieve anticipated savings and operational efficiencies or that may otherwise harm our business.

These risks include loss of workforce capabilities, loss of continuity, decreases in employee focus and morale, attrition of necessary or key employees, higher than anticipated separation expenses, litigation and the failure to meet financial and operational targets.

In addition, the calculation of the anticipated cost savings and other benefits resulting from our corporate restructuring actions are subject to many estimates and assumptions.

These estimates and assumptions are subject to significant business, economic, competitive and other uncertainties and contingencies, many of which are beyond our control.

If these estimates and assumptions are incorrect or if we experience delays or unforeseen events, our business and financial results could be adversely affected.

To manage our current and future potential growth effectively, we need to continue to enhance our operational, financial and management processes and to expand, train and manage our employee base.

We recently announced our intent to build a biologics manufacturing facility in Solothurn, Switzerland and our acquisition of an additional manufacturing facility in RTP, North Carolina.

Our Board of Directors has approved stock repurchase programs and may approve additional repurchase programs in the future.

Biogen is a global biopharmaceutical company focused on discovering, developing, manufacturing and delivering therapies to [removed: patients for the treatment of neurodegenerative diseases, hematologic conditions] [added: people living with serious neurological, rare] and autoimmune [removed: disorders.][added: diseases.]

Our marketed products include TECFIDERA, AVONEX, PLEGRIDY, [removed: TYSABRI] [added: TYSABRI, ZINBRYTA] and FAMPYRA for multiple sclerosis (MS), [removed: ELOCTATE for hemophilia A and ALPROLIX for hemophilia B, and] FUMADERM for the treatment of severe plaque [removed: psoriasis.][added: psoriasis and SPINRAZA for the treatment of spinal muscular atrophy (SMA).]

We also have [removed: a collaboration agreement with Genentech, Inc. (Genentech), a wholly-owned member of the Roche Group, which entitles us to] certain business and financial rights with respect to RITUXAN for the treatment of non-Hodgkin's lymphoma, chronic lymphocytic leukemia (CLL) and other conditions, GAZYVA indicated for the treatment of [removed: CLL,] [added: CLL] and [added: follicular lymphoma, and] other potential anti-CD20 [removed: therapies.][added: therapies under a collaboration agreement with Genentech, Inc. (Genentech), a wholly-owned member of the Roche Group.]

In the longer term, our revenue growth will be dependent upon the successful clinical development, regulatory approval and launch of new commercial products as well as additional indications for our existing products, our ability to obtain and maintain patents and other rights related to our marketed [removed: products and] [added: products,] assets originating from our research and development [removed: efforts,] [added: efforts] and successful execution of external business development opportunities.

[added: biosimilars through] Samsung Bioepis, our joint venture with Samsung BioLogics Co. Ltd. (Samsung Biologics).

[removed: ][added: ]

Diluted earnings per share attributable to Biogen Inc. were [removed: $15.34] [added: $16.93] for [removed: 2015,] [added: 2016,] representing an increase of [removed: 24.0%] [added: 10.4%] over the same period in [removed: 2014.][added: 2015.]

As described below under “Results of Operations,” our income from operations for the year ended December 31, [removed: 2015,] [added: 2016,] reflects the following:

| • | Total revenues were [removed: $10,763.8] [added: $11,448.8] million for [removed: 2015,] [added: 2016,] representing an increase of [removed: 10.9%] [added: 6.4%] over the same period in [removed: 2014.] [added: 2015.] |

We generated [removed: $3,716.1] [added: $4,522.4] million of net cash flows from operations for [removed: 2015,] [added: 2016,] which were primarily driven by earnings.

Cash, cash equivalents and marketable securities totaled approximately [removed: $6,188.9] [added: $7,724.5] million as of December 31, [removed: 2015.][added: 2016.]

During the year ended December 31, [removed: 2015,] [added: 2016,] we repurchased and retired approximately [removed: 16.8] [added: 3.3] million shares of common stock at a cost of [removed: $5.0] [added: $1.0] billion under our share repurchase programs.

On October 21, 2015, we announced a corporate restructuring, which [removed: includes] [added: included] the termination of certain pipeline programs and an 11% reduction in workforce.

For additional information related to this transaction, please read Note [removed: 2, Acquisitions] [added: 19, Collaborative and Other Relationships] to our consolidated financial statements included in this report.

For additional information [removed: related to] [added: about] these transactions, please read Note 19, Collaborative and Other Relationships to our consolidated financial statements included in this report.

Our products may also face increased competitive pressures from the introduction of generic versions, prodrugs of existing therapeutics or biosimilars of existing products and other technologies, such as gene [removed: therapies.][added: therapies and bispecific antibodies.]

For additional information related to our competition and pricing risks that could negatively impact our [removed: products,] [added: product sales,] please read the “Risk Factors” section of this report.

| | [removed: 2015] [added: 2016] compared to [removed: 2014] [added: 2015] | | | [removed: 2014] [added: 2015] compared to [removed: 2013] [added: 2014] | | | | | | | | | | | | | |

| (In millions, except percentages) | [removed: 2015] [added: 2016] | | | | [removed: 2014] [added: 2015] | | | | [removed: 2013] [added: 2014] | | | | | | | | |

| United States | $ | [removed: 6,545.8] [added: 7,050.4] | | | $ | [removed: 5,566.7] [added: 6,545.8] | | | $ | [removed: 3,581.0] [added: 5,566.7] | | | [removed: 17.6] [added: 7.7] | % | | [removed: 55.5] [added: 17.6] | % |

| Rest of world | [removed: 2,642.7] [added: 2,767.5] | | | | [removed: 2,636.7] [added: 2,642.7] | | | | [removed: 1,961.3] [added: 2,636.7] | | | | [removed: 0.2] [added: 4.7] | % | | [removed: 34.4] [added: 0.2] | % |

| Total product revenues | [removed: 9,188.5] [added: 9,817.9] | | | | [removed: 8,203.4] [added: 9,188.5] | | | | [removed: 5,542.3] [added: 8,203.4] | | | | [removed: 12.0] [added: 6.8] | % | | [removed: 48.0] [added: 12.0] | % |

| Other revenues | [removed: 236.1] [added: 316.4] | | | | [removed: 304.5] [added: 236.1] | | | | [removed: 263.9] [added: 304.5] | | | | [removed: (22.5] [added: 34.0] | [removed: )%] [added: %] | | [removed: 15.4] [added: (22.5] | [removed: %] [added: )%] |

| Total revenues | $ | [removed: 10,763.8] [added: 11,448.8] | | | $ | [removed: 9,703.3] [added: 10,763.8] | | | $ | [removed: 6,932.2] [added: 9,703.3] | | | [removed: 10.9] [added: 6.4] | % | | [removed: 40.0] [added: 10.9] | % |

| TECFIDERA | $ | [removed: 3,638.4] [added: 3,968.1] | | | $ | [removed: 2,909.2] [added: 3,638.4] | | | $ | [removed: 876.1] [added: 2,909.2] | | | [removed: 25.1] [added: 9.1] | % | | [removed: 232.1] [added: 25.1] | % |

| Interferon* | [removed: 2,968.7] [added: 2,795.2] | | | | [removed: 3,057.6] [added: 2,968.7] | | | | [removed: 3,005.5] [added: 3,057.6] | | | | [removed: (2.9] [added: (5.8] | )% | | [removed: 1.7] [added: (2.9] | [removed: %] [added: )%] |

| TYSABRI | [removed: 1,886.1] [added: 1,963.8] | | | | [removed: 1,959.5] [added: 1,886.1] | | | | [removed: 1,526.5] [added: 1,959.5] | | | | [removed: (3.7] [added: 4.1] | [removed: )%] [added: %] | | [removed: 28.4] [added: (3.7] | [removed: %] [added: )%] |

| FAMPYRA | [removed: 89.7] [added: 84.9] | | | | [removed: 80.2] [added: 89.7] | | | | [removed: 74.0] [added: 80.2] | | | | [removed: 11.8] [added: (5.4] | [removed: %] [added: )%] | | [removed: 8.4] [added: 11.8] | % |

| ELOCTATE | [removed: 319.7] [added: 513.2] | | | | [removed: 58.4] [added: 319.7] | | | | [removed: —] [added: 58.4] | | | | [removed: 447.4] [added: 60.5] | % | | [added: 447.4] | [added: %] |

| ALPROLIX | [removed: 234.5] [added: 333.7] | | | | [removed: 76.0] [added: 234.5] | | | | [removed: —] [added: 76.0] | | | | [removed: 208.6] [added: 42.3] | % | | [added: 208.6] | [added: %] |

| FUMADERM | [removed: 51.4] [added: 45.9] | | | | [removed: 62.5] [added: 51.4] | | | | [removed: 60.2] [added: 62.5] | | | | [removed: (17.8] [added: (10.7] | )% | | [removed: 3.8] [added: (17.8] | [removed: %] [added: )%] |

| Total product revenues | $ | [removed: 9,188.5] [added: 9,817.9] | | | $ | [removed: 8,203.4] [added: 9,188.5] | | | $ | [removed: 5,542.3] [added: 8,203.4] | | | [removed: 12.0] [added: 6.8] | % | | [removed: 48.0] [added: 12.0] | % |

[removed: ][added: ]

For 2015 compared to 2014, the increase in U.S. [removed: TECFIDERA] [added: TYSABRI] revenues was primarily due to an increase in unit sales volume of [removed: 13% as TECFIDERA penetrated the U.S. market,] [added: 4%] and increases in gross [removed: price] [added: price,] partially offset by higher discounts and allowances.

For [removed: 2014] [added: 2015] compared to [removed: 2013,] [added: 2014,] the increase in U.S. [removed: TECFIDERA] [added: ELOCTATE] revenues was primarily due to increases in unit sales volume.

For 2015 compared to 2014, the increase in rest of world TECFIDERA revenues was primarily due to increases in unit sales volume in existing markets and in [removed: additional] [added: new] markets as we continue to launch the product and expand our presence around the world.

Rest of world TECFIDERA revenues for [removed: 2015] [added: 2015,] compared to [removed: 2014] [added: 2014,] were [added: also] negatively impacted by foreign currency exchange losses totaling $74.1 million.

We launched TECFIDERA in Germany in February [removed: 2014,] [added: 2014] and our unregulated pricing ended in the first quarter of 2015, at which time we began recognizing revenue at the fixed price established through our negotiations with the German regulatory authorities.

[removed: ][added: ]

For 2015 compared to 2014, the decrease in [removed: U.S. AVONEX] [added: rest of world Interferon] revenues was [removed: primarily] due to a decrease in [added: AVONEX] unit sales volume of [removed: 17%, which was attributable] [added: 11% primarily] in [removed: part] [added: Europe attributable] to patients transitioning to [removed: PLEGRIDY and] [added: other] oral MS therapies, including [removed: TECFIDERA, partially offset by gross price increases.][added: TECFIDERA.]

In May 2016 we announced our intention to spin off our hemophilia business, Bioverativ Inc. (Bioverativ), as an independent, publicly traded company.

Bioverativ will focus on the discovery, development and commercialization of therapies for the treatment of hemophilia and other blood disorders, including ELOCTATE for the treatment of hemophilia A and ALPROLIX for the treatment of hemophilia B.

Bioverativ will also assume all of our rights and obligations under our collaboration agreement with Swedish Orphan Biovitrum AB (Sobi) and our collaboration and license agreement with Sangamo Biosciences Inc. (Sangamo).

On February 1, 2017, we completed the distribution of all the then outstanding shares of common stock of Bioverativ to Biogen stockholders, who received one share of Bioverativ common stock for every two shares of Biogen common stock.

As a result of the distribution, Bioverativ is now an independent public company whose shares of common stock are trading under the symbol "BIVV"

on the Nasdaq Global Select Market.

The financial results of Bioverativ are included in our consolidated results of operations and financial position in our audited consolidated financial statements for the periods presented in this Form 10-K.

The financial results of Bioverativ will be excluded from our consolidated results of operations and financial position commencing February 1, 2017.

Our current revenues depend upon continued sales of our principal products and, unless we develop, acquire rights to, and commercialize new products and technologies, we may be substantially dependent on sales from our principal products for many years.

Further, following the completion of the spin-off of our hemophilia business, our revenues will be further reliant and concentrated on sales of our MS products in an increasingly competitive market.

We support our drug discovery and development efforts through the commitment of significant resources to discovery, research and development programs and business development opportunities, particularly within areas of our scientific, manufacturing and technical capabilities.

For nearly two decades we have led in the research and development of new therapies to treat MS, resulting in our leading portfolio of MS treatments.

Now our research is focused on additional improvements in the treatment of MS, such as, the development of next generation therapies for MS with a goal to reverse or possibly repair damage caused by the disease.

We are also applying our scientific expertise to solve some of the most challenging and complex diseases, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis (ALS), and are employing innovative technologies to discover potential treatments for rare and genetic disorders, including new ways of treating diseases through gene therapy.

Our innovative drug development and commercialization activities are complemented by our biosimilar therapies that expand access to medicines and reduce the cost burden for healthcare systems.

We are leveraging our manufacturing capabilities and know-how by developing, manufacturing and marketing

Under our commercial agreement with Samsung Bioepis, we market and sell BENEPALI, an etanercept biosimilar referencing ENBREL, and FLIXABI, an infliximab biosimilar referencing REMICADE, in the European Union (E.U.).

| • | Product revenues, net totaled $9,817.9 million for 2016, representing an increase of 6.8% over the same period in 2015. This increase was driven by a 9.1% increase in worldwide TECFIDERA revenues, a 52.8% increase in worldwide hemophilia revenues, a 4.1% increase in worldwide TYSABRI revenues and revenues from BENEPALI. These increases are partially offset by a 5.8% decrease in worldwide Interferon revenues. Product revenues, net for |

2016, compared to the same period in 2015, were also negatively impacted by a $167.8 million decrease in hedge gains recognized under our foreign currency hedging program in comparative periods.

| • | Revenues from anti-CD20 therapeutic programs totaled $1,314.5 million for 2016, representing a decrease of 1.8% over the same period in 2015. |

| • | Other revenues totaled $316.4 million for 2016, representing an increase of 34.0% from the same period in 2015. This increase was primarily driven by an increase in other corporate revenues, which includes amounts earned with respect to our contract manufacturing activities. |

| • | Total cost and expenses totaled $6,298.4 million for 2016, representing an increase of 7.2%, compared to the same period in 2015. This increase was driven by a $454.8 million litigation settlement and license charge and a 19.2% increase in cost of sales, which includes a charge of $45.5 million for accelerated depreciation as a result of the determination to cease manufacturing in Cambridge, MA and vacate our biologics manufacturing facility in Cambridge, MA and warehouse space in Somerville, MA. These increases were partially offset by a 7.8% decrease in selling, general and administrative expenses and a decrease in restructuring charges. |

In May 2016 we entered into a collaboration and alliance with the University of Pennsylvania (UPenn) to advance gene therapy and gene editing technologies.

Restructuring and Cost Saving Initiatives

During the third quarter of 2016 we initiated cost saving measures primarily intended to realign our organizational structure due to the changes in roles and workforce resulting from our decision to spin off our hemophilia business, and to achieve further targeted cost reductions.

Additionally, in connection with the transaction to sublease our rights to the manufacturing facility in Cambridge, MA to Brammer Bio MA, LLC (Brammer), certain employees were separated from Biogen.

For additional information related to our restructuring and cost saving initiatives, please read Note 3, Restructuring, Business Transformation and Other Cost Saving Initiatives to our consolidated financial statements included in this report.

Drug prices are under significant scrutiny in the markets in which our products are prescribed.

Drug pricing and other health care costs continue to be subject to intense political and societal pressures.

| Revenues from anti-CD20 therapeutic programs | 1,314.5 | | | | 1,339.2 | | | | 1,195.4 | | | | (1.8 | )% | | 12.0 | % |

| | 2016 compared to 2015 | | | 2015 compared to 2014 | | | | | | | | | | | | | |

| ZINBRYTA | 7.8 | | | | — | | | | — | | | | | | | | |

| SPINRAZA | 4.6 | | | | — | | | | — | | | | | | | | |

| BENEPALI | 100.6 | | | | — | | | | — | | | | | | | | |

| FLIXABI | 0.1 | | | | — | | | | — | | | | | | | | |

For 2015 compared to 2014, the increase in U.S. TECFIDERA revenues was primarily due to increases in unit sales volume of 13% as TECFIDERA penetrated the U.S. market, and increases in gross

price partially offset by higher discounts and allowances.

For 2016 compared to 2015, the increase in rest of world TECFIDERA revenues was primarily due to increases in unit sales volume of 32% in existing markets and new markets where we continue to launch the product and expand our presence around the world.

These increases were partially offset by pricing reductions in certain European countries.

Rest of world TECFIDERA revenues for 2016, compared to 2015, were also negatively impacted by a $50.2 million decrease in hedge gains recognized under our foreign currency hedging program in the comparative period.

Our current revenues depend upon continued sales of our principal products.

We may be substantially dependent on sales from our principal products for many years, including an increasing reliance on sales and growth of TECFIDERA as we continue to expand into additional markets.

As part of our ongoing research and development efforts, we have devoted significant resources to conducting clinical studies to advance the development of new pharmaceutical products and to explore the utility of our existing products in treating disorders beyond those currently approved in their labels.

In addition to our innovative drug development efforts, we aim to leverage our manufacturing capabilities and scientific expertise to extend our mission to improve the lives of patients living with serious diseases through the development, manufacture and marketing of biosimilars through

| • | Product revenues, net totaled $9,188.5 million for 2015, representing an increase of 12.0% over the same period in 2014. This increase was driven by a 25.1% increase in worldwide TECFIDERA revenues as well as revenue from our recent product additions PLEGRIDY, ELOCTATE and ALPROLIX, partially offset by a decrease in worldwide AVONEX and TYSABRI revenues. In addition, product revenues, net for 2015, compared to the same period in 2014, were negatively impacted by foreign currency exchange losses of $388.1 million, partially offset by comparative net gains recognized under our foreign currency hedging program of $166.3 million. |

| • | Our share of RITUXAN and GAZYVA operating profits totaled $1,339.2 million for 2015, representing an increase of 12.0% over the same period in 2014. This increase was primarily due to a 4% increase in U.S. product sales of RITUXAN and price increases. |

| • | Other revenues totaled $236.1 million for 2015, representing a decrease of 22.5% from the same period in 2014. This decrease was driven by a 73.1% decrease in royalty revenues primarily due to the expiration of U.S. patent rights that gave rise to royalty payments related to ANGIOMAX, partially offset by a 47.6% increase in corporate partner revenues primarily due to an increase in contract manufacturing activities. |

| • | Total cost and expenses totaled $5,872.8 million for 2015, representing an increase of 2.2% compared to the same period in 2014. This increase was driven by a 6.3% increase in research and development expense, a 5.9% increase in cost of sales, losses recognized on fair value remeasurement of contingent consideration as well as the recognition of a $93.4 million charge related to our recent corporate restructuring. These increases were partially offset by a 21.9% decrease in the amortization of acquired intangible assets and a 5.3% decrease in selling, general and administrative expenses. |

On September 15, 2015, we issued senior unsecured notes for an aggregate principal amount of $6.0 billion.

Restructuring

For additional information, please read Restructuring set forth below in this Management's Discussion and Analysis of Financial Condition and Results of Operations.

Acquisitions

On February 12, 2015, we completed the acquisition of all of the outstanding stock of Convergence Pharmaceuticals (Convergence), a clinical-stage biopharmaceutical company with a focus on developing product candidates for neuropathic pain.

On July 2, 2015, we announced a collaboration and license agreement to develop gene-based therapies for multiple ophthalmic diseases with Applied Genetic Technologies Corporation (AGTC).

On September 9, 2015, we announced an agreement with Mitsubishi Tanabe Pharma Corporation (MTPC) to exclusively license amiselimod (MT-1303), a late stage experimental medicine with potential in multiple autoimmune indications.

Amiselimod is an oral compound that targets the sphingosine 1-phosphate receptor.

| Unconsolidated joint business revenues | 1,339.2 | | | | 1,195.4 | | | | 1,126.0 | | | | 12.0 | % | | 6.2 | % |

Percentage not meaningful.

For 2014 compared to 2013, rest of world TECFIDERA revenues increased as sales in Germany began in the first quarter of 2014.

While we continue to see a strong uptake of TECFIDERA in newly launched territories, total market growth and patient switch rates in our maturing markets, such as the U.S. and Germany, have returned to historical averages for MS.

AVONEX

For 2014 compared to 2013, the decrease in rest of world AVONEX revenues was due to a 7% decrease in unit sales volume in Europe primarily attributable to patients transitioning to oral therapies including TECFIDERA, partially offset by a 6% increase in unit demand in the emerging markets region.

Rest of world AVONEX revenue for 2014 compared to 2013 also reflects the negative impact of foreign currency exchange rate changes experienced in 2014, partially offset by gains recognized in relation to the settlement of certain cash flow hedge instruments under our foreign currency hedging program.

PLEGRIDY

Sales of PLEGRIDY began in the E.U. and the U.S. in the third and fourth quarters of 2014, respectively.

We expect that PLEGRIDY revenues will increase as PLEGRIDY becomes commercially available in additional markets and as patients transition to PLEGRIDY from AVONEX and other therapies.

Based on data reported by Elan for 2013 and our sales to third-party customers, total U.S. TYSABRI in-market sales were $958.3 million.

For 2014 compared to 2013, the increase in rest of world TYSABRI revenues was primarily due to the recognition of $53.5 million of revenue previously deferred in Italy relating to the pricing agreement with AIFA as discussed below, volume increases in Europe of 10% and in our emerging markets region of 18% and a favorable net price in Germany as the mandatory rebate percentage was reduced.

Rest of world TYSABRI revenue for 2014 compared to 2013 also reflects the negative impact of foreign currency exchange rate changes experienced in 2014, partially offset by gains recognized in relation to the settlement of certain cash flow hedge instruments under our foreign currency hedging program.

We expect that TYSABRI revenues will continue to face competition from additional treatments for MS and certain other pipeline products, including ZINBRYTA and ocrelizumab.

We expect continued growth with ELOCTATE as there remains a significant portion of the patient population that can benefit from long-acting therapies.

We also expect moderating patient additions for ALPROLIX.

Unconsolidated Joint Business Revenues

*Biogen's share of pre-tax profits includes the reimbursement of selling and development expenses.

For 2014 compared to 2013, the increase in U.S. product revenues was primarily due to price increases and an increase in RITUXAN unit sales volume, partially offset by the 2013 recognition of $94.9 million in net revenues resulting from the July 2013 issuance by the Department of Health and Human Services of its final rule on the Exclusion of Orphan Drugs for Certain Covered Entities Under 340B Program.

The issuance of the final rule by the Department of Health and Human Services did not have an impact on the amount we recorded as revenues from unconsolidated joint business in our consolidated statements of income because, through June 30, 2013, we had been increasing our share of profits in the U.S. to reflect our interpretation of the proposed 340B rule.

The final rule was consistent with our prior interpretation.

Collaboration costs and expenses for 2014 compared to 2013 increased primarily due to the recognition of $53.9 million of additional BPD fee expense, as discussed above, as well as GAZYVA sales and marketing and research and development expenses.

Upon the first marketing approval of GAZYVA by the FDA in the U.S., we began recognizing all activity, including sales and marketing and research and development expenses related to the GAZYVA program in unconsolidated joint business in our consolidated statements of income.

Prior to its first regulatory approval, we recognized our share of GAZYVA development and commercialization expenses as research and development expense and selling, general and administrative expense, respectively, in our consolidated statements of income.

We have operations or maintain distribution relationships in the U.S., Europe, Canada, [removed: Switzerland, Denmark, Japan, Australia, New Zealand and] [added: Asia,] Central and South America.

As a result, our financial position, results of operations and cash flows can be affected by market fluctuations in foreign exchange rates, primarily with respect to the Euro, British pound sterling, Canadian dollar, Swiss franc, Danish [removed: krone, Japanese yen] [added: krone] and [removed: Australian dollar.][added: Japanese yen.]

In particular, as the U.S. dollar strengthens versus other currencies, the value of [removed: the] non-U.S. revenue will decline when reported in U.S. dollars.

As the U.S. dollar weakens versus other currencies, the value of [removed: the] non-U.S. revenue and expenses will increase when reported in U.S. dollars.

In these instances, we principally utilize currency forward [added: contracts.]

As of December 31, [removed: 2015] [added: 2016] and [removed: 2014,] [added: 2015,] a hypothetical adverse 10% movement in foreign currency rates compared to the U.S. dollar across all maturities would result in a hypothetical decrease in the fair value of forward contracts of approximately [removed: $185.0] [added: $172.0] million and [removed: $160.0] [added: $185.0] million, respectively.

Our use of this methodology to quantify the market risk of such instruments is subject to assumptions and [added: the] actual impact could be significantly different.

As of December 31, [removed: 2015] [added: 2016] and [removed: 2014,] [added: 2015,] we estimate that such hypothetical 100 basis point adverse movement would result in a hypothetical loss in fair value of approximately [removed: $43.0] [added: $50.0] million and [removed: $14.5] [added: $43.0] million, respectively, to our interest rate sensitive instruments.

As of December 31, [added: 2016 and] 2015, a 100 basis-point adverse movement (increase in LIBOR) would increase annual interest expense by approximately $6.8 [removed: million.][added: million in each case.]

Thus, our inability to secure favorable prices in a particular country may impair our ability to obtain acceptable prices in existing and potential new [removed: markets and] [added: markets, which may] limit market growth.

Our accounts receivable are primarily due from wholesale distributors, public [removed: hospitals] [added: hospitals, specialty pharmacies] and other government entities.

We monitor the financial performance and creditworthiness of our [removed: large] customers so that we can properly assess and respond to changes in their credit profile.

We operate in certain countries where weakness in economic [added: conditions can result in extended collection periods.]

We believe that our allowance for doubtful accounts was adequate as of December 31, [removed: 2015] [added: 2016] and [removed: 2014, respectively.][added: 2015.]

In addition, we recognize our share of pre-tax co-promotion profits on RITUXAN in Canada.

In June 2016 the U.K. voted in a referendum to voluntarily depart from the E.U., known as Brexit.

The macroeconomic impact on our results of operations from this vote remains unknown.

To date, the foreign exchange impact has been negligible since we hedged the balance sheet foreign currency exchange risk.

Further, we only enter into contracts with counterparties that have at least an "A" (or equivalent) credit rating.

In addition, we receive royalty revenues based on sales of RITUXAN in Canada.

contracts.

conditions can result in extended collection periods.

Biogen is a global biopharmaceutical company focused on discovering, developing, manufacturing and delivering therapies to [removed: patients for the treatment of neurodegenerative diseases, hematologic conditions] [added: people living with serious neurological, rare] and autoimmune [removed: disorders.][added: diseases.]

Our marketed products include TECFIDERA, AVONEX, PLEGRIDY, [removed: TYSABRI] [added: TYSABRI, ZINBRYTA] and FAMPYRA for multiple sclerosis (MS), [removed: ELOCTATE for hemophilia A and ALPROLIX for hemophilia B, and] FUMADERM for the treatment of severe plaque [removed: psoriasis.][added: psoriasis and SPINRAZA for the treatment of spinal muscular atrophy (SMA).]

We also have [removed: a collaboration agreement with Genentech, Inc. (Genentech), a wholly-owned member of the Roche Group (Roche Group), which entitles us to] certain business and financial rights with respect to RITUXAN for the treatment of non-Hodgkin's lymphoma, chronic lymphocytic leukemia (CLL) and other conditions, GAZYVA indicated for the treatment of [removed: CLL,] [added: CLL] and [added: follicular lymphoma and] other potential anti-CD20 [removed: therapies.][added: therapies under a collaboration agreement with Genentech, Inc. (Genentech), a wholly-owned member of the Roche Group (Roche Group).]

We support our drug discovery and development efforts through the commitment of significant resources to discovery, research and development programs and business development opportunities, particularly within areas of our scientific, manufacturing and technical [removed: expertise and scientific adjacencies.][added: capabilities.]

During [removed: 2015 and early 2016,] [added: 2016] we had a number of key developments affecting our business.

[removed: | l | Entered into] [added: We have] a collaboration agreement with Applied Genetic Technologies Corporation (AGTC) to develop gene-based therapies for multiple ophthalmic [removed: diseases | |][added: diseases.]

[removed: |  |][added: ]

[removed: |  |][added: ]

[removed: |] Multiple Sclerosis [removed: | |]

| ZINBRYTA [removed: (daclizumab high yield process)] [added: (daclizumab)] | |

| [removed: Anti-LINGO] [added: Opicinumab (Anti-LINGO-1)] | |

| l | In September [removed: 2015,] [added: 2015] we enrolled our first patient in our two global Phase 3 studies, ENGAGE and [removed: EMERGE, to] [added: EMERGE. ENGAGE and EMERGE will] assess the efficacy and safety of [removed: aducanumab] [added: aducanumab, our investigational treatment for early Alzheimer's disease,] in [added: approximately 2,700] people with early Alzheimer's disease. [added: The studies are identical in design and eligibility criteria. Each study will be conducted in more than 20 countries in North America, Europe and Asia.] In October [removed: 2015,] [added: 2015] we announced that we received FDA agreement on a special protocol assessment on the Phase 3 study protocols. [removed: Such agreement constitutes FDA’s concurrence on the design and size of the clinical trials which will form the basis for approval of aducanumab.] |

| [removed: Ocrelizumab] [added: OCREVUS (ocrelizumab)] | |

| l | In June [removed: 2015,] [added: 2015] the Roche Group announced positive results from two Phase 3 studies evaluating [removed: ocrelizumab] [added: OCREVUS] compared with interferon beta-1a in people with relapsing forms of MS. [added: Treatment with OCREVUS compared with interferon beta-1a significantly reduced the annualized relapse rate over a two-year period; significantly reduced the progression of clinical disability; and led to a significant reduction in the number of lesions in the brain as measured by MRI.] |

| l | In September [removed: 2015,] [added: 2015] the Roche Group announced positive results from a Phase 3 study evaluating [removed: ocrelizumab] [added: OCREVUS] in people with [removed: primary progressive MS (PPMS).] [added: PPMS. Treatment with OCREVUS significantly reduced the progression of clinical disability compared with placebo, as measured by the Expanded Disability Status Scale.] |

[removed: | l | Under] [added: Additionally, under] our agreement with Genentech, if [removed: ocrelizumab] [added: OCREVUS] is approved, we will receive tiered royalty payments on sales of [removed: ocrelizumab. |][added: OCREVUS in the U.S.]

| l | In [removed: November 2015, Samsung Bioepis received a positive opinion from the Committee for Medicinal Products for Human Use (CHMP) for] [added: January 2016] the [added: EC approved Samsung Bioepis'] MAA for BENEPALI, an etanercept biosimilar referencing [removed: ENBREL. In January 2016, the EC approved the MAA for BENEPALI] [added: ENBREL,] for marketing in the E.U. Under our agreement with Samsung Bioepis, we [removed: will manufacture] [added: are manufacturing] and [removed: commercialize] [added: commercializing] BENEPALI in specified E.U. countries. |

| l | In [removed: March 2015,] [added: July 2016] the EMA [removed: validated and] accepted Samsung [removed: Bioepis’] [added: Bioepis'] MAA for [removed: FLIXABI,] [added: SB5,] an [removed: infliximab] [added: adalimumab] biosimilar candidate referencing [removed: REMICADE.] [added: HUMIRA.] |

The following graphs show our [removed: product sales and unconsolidated joint business] revenues by [removed: principal] product and [added: revenues from anti-CD20 therapeutic programs and] geography as a percentage of revenue for the years ended December 31, [removed: 2015, 2014] [added: 2016, 2015] and [removed: 2013.][added: 2014.]

[removed: ][added: ]

[removed: (1)] [added: (2)] Other includes [added: ZINBRYTA,] FAMPYRA, ELOCTATE, [removed: ALPROLIX] [added: ALPROLIX, FUMADERM, SPINRAZA, BENEPALI] and [removed: FUMADERM][added: FLIXABI]

[removed: ][added: |  | Spinal muscular atrophy | | Ionis | | U.S. |]

Product sales for TECFIDERA, AVONEX and TYSABRI and [removed: unconsolidated joint business revenues] [added: anti-CD20 therapeutic programs] for RITUXAN each accounted for more than 10% of our total revenue for the years ended December 31, [removed: 2015, 2014] [added: 2016, 2015] and [removed: 2013.][added: 2014.]

| [removed: ] [added: ] | Relapsing forms of MS in the U.S. Relapsing-remitting MS (RRMS) in the E.U. | | None | | U.S. [removed: United Kingdom] France Germany Italy Spain [added: United Kingdom] |

| [removed: ] [added: ] | Relapsing forms of MS | | None | | U.S. [removed: United Kingdom] France Germany Italy Spain [added: United Kingdom] |

| [removed: ] [added: ] | Relapsing forms of MS in the U.S. RRMS in the E.U. | | None | | U.S. [removed: United Kingdom] France Germany Italy Spain [added: United Kingdom] |

| [removed: ] [added: ] | Relapsing forms of MS Crohn's disease in the U.S. | | None | | U.S. [removed: United Kingdom] France Germany Italy Spain [added: United Kingdom] |

| [removed: ] [added: ] | Walking ability for patients with MS | | Acorda Therapeutics, Inc. (Acorda) | | France Germany Spain [removed: Canada] |

Our products for [removed: hemophilia] [added: SMA] and major markets include:

| [removed: ] [added: ] | Non-Hodgkin's lymphoma CLL Rheumatoid arthritis Two forms of ANCA-associated vasculitis | | U.S. Canada |

| [removed: ] [added: ] | In combination with chlorambucil for previously untreated CLL [added: Follicular lymphoma] | | U.S. |

For information about our [removed: unconsolidated joint business] [added: anti-CD20 therapeutic programs] and [removed: agreement] [added: related agreements] with Genentech, please read Note 1, Summary of Significant Accounting Policies and Note 19, Collaborative and Other Relationships to our consolidated financial statements included in this report.

| Product | Indication | | Collaborator | | Major [removed: Market] [added: Markets] |

| [removed: ] [added: ] | Moderate to severe plaque psoriasis | | None | | Germany |

Our product sales to two wholesale distributors, AmerisourceBergen and McKesson, each accounted for more than 10% of our total revenues for the years ended December 31, [removed: 2015, 2014] [added: 2016, 2015] and [removed: 2013,] [added: 2014,] and on a combined basis, accounted for approximately 60% of our gross product revenues for such years, respectively.

Among other things, we provide customer service and other related programs for our products, such as disease and product specific websites, insurance research [removed: services and order, delivery] [added: services, financial assistance programs,] and [removed: fulfillment services.][added: the facilitation of the procurement of our marketed products.]

With those tools, we help patients [removed: and] [added: understand] their [removed: caregivers and healthcare professionals understand,] [added: insurance coverage and, if needed, help patients] compare and select [added: new] insurance options and [removed: programs that are available to them.][added: programs.]

In the U.S., we have established programs that provide [added: co-pay assistance or free marketed product for] qualified uninsured or underinsured [removed: patients with marketed products at no or reduced charge,] [added: patients,] based on specific eligibility criteria.

We also provide charitable contributions [added: to independent charitable organizations] that [removed: may] assist [removed: eligible commercially-insured] patients with out-of-pocket expenses associated with their [removed: costs for our products.][added: therapy.]

| | | Europe | | 0804237 | | Humanized immunoglobulins; nucleic acids; pharmaceutical compositions; medical uses | | [removed: 2020] [added: 2020(4)] |

For nearly two decades we have led in the research and development of new therapies to treat MS, resulting in our leading portfolio of MS treatments.

Now our research is focused on additional improvements in the treatment of MS, such as the development of next generation therapies for MS, with a goal to reverse or possibly repair damage caused by the disease.

We are also applying our scientific expertise to solve some of the most challenging and complex diseases, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis (ALS), and are employing innovative technologies to discover potential treatments for rare and genetic disorders, including new ways of treating diseases through gene therapy.

Our innovative drug development and commercialization activities are complemented by our biosimilar therapies that expand access to medicines and reduce the cost burden for healthcare systems.

We are leveraging our manufacturing capabilities and know-how to develop, manufacture and market biosimilars through Samsung Bioepis, our joint venture with Samsung BioLogics Co. Ltd. (Samsung Biologics).

Under this agreement, we are currently manufacturing and commercializing two anti-tumor necrosis factor (TNF) biosimilars in certain European Union (E.U.) countries.

Hemophilia Spin-Off

In May 2016 we announced our intention to spin off our hemophilia business, Bioverativ Inc. (Bioverativ), as an independent, publicly traded company.

Bioverativ will focus on the discovery, development and commercialization of therapies for treatment of hemophilia and other blood disorders, including ELOCTATE for the treatment of hemophilia A and ALPROLIX for the treatment of hemophilia B.

Bioverativ will also assume all of our rights and obligations under our collaboration agreement with Swedish Orphan Biovitrum AB (Sobi) and our collaboration and license agreement with Sangamo Biosciences Inc. (Sangamo).

On February 1, 2017, we completed the distribution of all the then outstanding shares of common stock of Bioverativ to Biogen stockholders, who received one share of Bioverativ common stock for every two shares of Biogen common stock.

As a result of the distribution, Bioverativ is now an independent public company whose shares of common stock are trading under the symbol "BIVV" on the Nasdaq Global Select Market.

The financial results of Bioverativ are included in our consolidated results of operations and financial position in our audited consolidated financial statements for the periods presented in this Form 10-K.

The financial results of Bioverativ will be excluded from our consolidated results of operations and financial position commencing February 1, 2017.

For additional information regarding the separation of Bioverativ, please read Note 26, Subsequent Events to our consolidated financial statements included in this report.

Management Changes

During 2016 we appointed several new executives, each of whom has significant experience in the biopharmaceutical industry and is a leader in his or her functional area.

These include Michel Vounatsos, Chief Executive Officer, Michael D.

Ehlers, Executive Vice President, Research and Development and Paul McKenzie, Executive Vice President, Pharmaceutical Operations and Technology.

For additional information related to these and our other Executive Officers, please read "Our Executive Officers" included in this report.

Cost Saving Initiatives

In 2016 we initiated cost saving measures intended to realign our organizational structure in anticipation of the changes in roles and workforce resulting from our decision to spin off our hemophilia business, as well as to achieve further targeted cost reductions.

In December 2016 after an evaluation of our manufacturing capacity and needs, we ceased manufacturing at our Cambridge, MA manufacturing facility and subleased our rights to this facility to Brammer Bio MA, LLC (Brammer).

In addition to the sublease, Brammer purchased certain leasehold improvements and other assets at this facility and agreed to provide certain manufacturing and other transition and support services to us.

TECFIDERA Settlement and License Agreement

In January 2017 we agreed to enter into a settlement and license agreement with Forward Pharma A/S (Forward Pharma).

The settlement and license agreement provides us an irrevocable license to all intellectual property owned by Forward Pharma and results in the termination of the German Infringement Litigation.

Under the terms of the settlement and license agreement with Forward Pharma, we agreed to pay Forward Pharma $1.25 billion in cash.

During the fourth quarter of 2016 we recognized a pre-tax charge of $454.8 million related to this matter.

For more information on the settlement and license agreement please read Note 21, Commitments and Contingencies to our consolidated financial statements included in this report.

| l | In June 2016 the European Commission (EC) approved a variation to the marketing authorization of TYSABRI, which extended its indication to include relapsing-remitting MS patients with highly active disease activity despite a full and adequate course of treatment with at least one disease modifying therapy. TYSABRI was previously indicated only for patients who had failed to respond to beta-interferon or glatiramer acetate in the E.U. |

| l | ZINBRYTA was approved for the treatment of relapsing forms of MS in the U.S. in May 2016 and the E.U. in July 2016. |

| l | In June 2016 we reported top-line results from SYNERGY, our Phase 2 trial evaluating opicinumab in people with relapsing forms of MS. Opicinumab did not meet the primary endpoint or its secondary efficacy endpoint. However, based on these results, there was a subset of patients within the study that we believe have potential to benefit from treatment, and we are therefore planning another Phase 2 clinical trial related to opicinumab. |

| l | In June 2016 we announced that aducanumab, our investigational treatment for early Alzheimer’s disease, was accepted into the European Medicines Agency's (EMA's) Priority Medicines (PRIME) program. PRIME aims to bring treatments to patients more quickly by enhancing the EMA's support for the development of investigational medicines for diseases without available treatments or in need of better treatment options. |

| l | In September 2016 aducanumab was granted "Fast Track" designation by the U.S. Food and Drug Administration (FDA). The FDA’s Fast Track program supports the development of new treatments for serious conditions with an unmet medical need such as Alzheimer’s disease. |

| l | In September 2016 we announced that efficacy and safety data from an additional interim analysis from our Phase 1b study of aducanumab in early Alzheimer's disease were consistent with results previously reported from the Phase 1b study. |

| l | In December 2016 we presented new data from the Phase 1b study of aducanumab, which included interim results from the titration cohort of the placebo-controlled period of the Phase 1b study as well as data from the first year of the long-term extension. The results supported the ongoing Phase 3 studies of aducanumab for early Alzheimer’s disease. |

| Rare Diseases | |

| SPINRAZA (nusinersen) | |

| l | In August 2016 we and Ionis Pharmaceuticals, Inc. (Ionis) announced that SPINRAZA met the primary endpoint for the interim analysis of ENDEAR, the Phase 3 trial evaluating SPINRAZA in infantile-onset (consistent with Type 1) SMA. Based on these results, we exercised our option under our collaboration agreement with Ionis to assume development and commercialization of SPINRAZA, and paid Ionis a $75.0 million license fee in connection with our option exercise. |

In addition to our innovative drug development efforts, we aim to leverage our manufacturing capabilities and scientific expertise to extend our mission to improve the lives of patients living with serious diseases through the development, manufacture and marketing of biosimilars through Samsung Bioepis, our joint venture with Samsung BioLogics Co. Ltd. (Samsung Biologics).

Company Name Change

In March 2015, we changed our name from Biogen Idec Inc. to Biogen Inc.

Corporate Restructuring

In October 2015, we announced a corporate restructuring, which includes a reduction in workforce and discontinuation of certain programs.

We are reinvesting the resulting savings to support key commercial activities and the advancement of our pipeline candidates.

Capital Allocation

In 2015, our capital allocation strategy included the following elements:

| | | |

| --- | --- | --- |

| Share Repurchase Program | l | Returned approximately $5.0 billion to our shareholders through our share repurchase program |

| l | Utilized a portion of the proceeds from our $6.0 billion senior unsecured debt offering completed in September 2015 to fund our share repurchase program | |

| Acquisitions and Collaborations | l | Acquired Convergence Pharmaceuticals (Convergence), a clinical-stage biopharmaceutical company with a focus on developing product candidates for neuropathic pain |

| l | Obtained exclusive worldwide license, excluding Asia, from Mitsubishi Tanabe Pharma Corporation (MTPC) to amiselimod (MT-1303), a late stage experimental medicine with potential in multiple autoimmune indications | |

| Investment in Manufacturing | l | Acquired land in Solothurn, Switzerland, where we plan to build a biologics manufacturing facility in the Commune of Luterbach over the next several years |

| l | Acquired the drug product manufacturing facility and supporting infrastructure of Eisai, Inc. (Eisai) in Research Triangle Park (RTP), North Carolina | |

Corporate Responsibility

| |

| --- |

| Environmental Sustainability |

In 2015, we were named the biotechnology industry leader on the Dow Jones Sustainability World Index, an index that tracks the economic, environmental and social strategy and performance of the 2,500 largest companies in the S&P Global Broad Market Index.

In 2015, we announced that we achieved carbon neutrality, meaning we believe we have effectively neutralized all of the carbon emissions associated with our business.

| Humanitarian Aid |

In 2014, we and Swedish Orphan Biovitrum AB (publ) (Sobi) began working with the World Federation of Hemophilia (WFH) to help people with hemophilia in the developing world through our pledge to donate up to one billion international units (IUs) of clotting factor therapy for humanitarian use, of which up to 500 million IUs will be donated to WFH USA over a period of five years.

In 2015, we made the first shipments of hemophilia therapy to WFH USA.

| l | In March 2015, the European Medicines Agency (EMA) validated our marketing authorization application (MAA) for ZINBRYTA for the treatment of relapsing forms of MS in the European Union (E.U.). |

| l | In April 2015, the U.S. Food and Drug Administration (FDA) accepted our Biologics License Application (BLA) for ZINBRYTA for the treatment of relapsing forms of MS in the United States (U.S.). |

| TYSABRI (natalizumab) | |

| l | In July 2015, the results of ACTION, our Phase 2 trial investigating TYSABRI in acute ischemic stroke, did not demonstrate an impact on change in infarct volume, the primary endpoint. Exploratory endpoints suggested that TYSABRI had a beneficial impact on patient functional deficits. |

| l | In October 2015, the results of ASCEND, our Phase 3 study evaluating TYSABRI in secondary progressive MS (SPMS), did not achieve its primary and secondary endpoints, and the development of TYSABRI in SPMS was discontinued. |

| l | In January 2015, we announced top-line results from RENEW, our Phase 2 acute optic neuritis trial. |

| Hemophilia | |

| ELOCTATE \[Antihemophilic Factor (Recombinant), Fc Fusion Protein\] | |

| l | In November 2015, the European Commission (EC) approved ELOCTA, the approved trade name for ELOCTATE in the E.U., for the treatment of hemophilia A. |

| l | Sobi has assumed final development and commercialization of ELOCTA in their territory, which essentially includes Europe, North Africa, Russia, and certain markets in the Middle East (Sobi Territory). |

| ALPROLIX \[Coagulation Factor IX (Recombinant), Fc Fusion Protein\] | |

| l | In June 2015, the EMA validated our MAA for ALPROLIX for the treatment of hemophilia B. |

| l | In July 2015, Sobi exercised its option to assume final development and commercialization of ALPROLIX in the Sobi Territory. |

| l | In March 2015 and July 2015, we announced data from pre-specified interim analyses of PRIME, our Phase 1b study of aducanumab. |

| Other Programs | |

For a discussion of legal matters as of December 31, [removed: 2015,] [added: 2016,] please read Note 20, Litigation to our consolidated financial statements included in this report, which is incorporated into this item by reference.

| | For the fiscal year ended December 31, [removed: 2015] [added: 2016] |

[removed: ][added: ]

The aggregate market value of the registrant’s common stock held by non-affiliates of the registrant (without admitting that any person whose shares are not included in such calculation is an affiliate) computed by reference to the price at which the common stock was last sold as of the last business day of the registrant’s most recently completed second fiscal quarter was [removed: $94,898,425,323.][added: $52,843,669,823.]

As of January [removed: 29, 2016,] [added: 27, 2017,] the registrant had [removed: 218,672,717] [added: 215,951,945] shares of common stock, $0.0005 par value, outstanding.

Portions of the definitive proxy statement for our [removed: 2016] [added: 2017] Annual Meeting of Stockholders are incorporated by reference into Part III of this report.

For the Year Ended December 31, [removed: 2015][added: 2016]

| [Item [removed: 1.](#sA30F171FDE9DE638C657B512B1605F7B)] [added: 1.](#s980F3D57A803760B6204201707AA605E)] | [removed: [Business](#sA30F171FDE9DE638C657B512B1605F7B)] [added: [Business](#s980F3D57A803760B6204201707AA605E)] | [removed: [1](#sA30F171FDE9DE638C657B512B1605F7B)] [added: [1](#s980F3D57A803760B6204201707AA605E)] |

| [Item [removed: 1A.](#sB7A45A12C24CD940C931B512B19484BB)] [added: 1A.](#s90E7A4539EE0A80EE7AB201709F0C16A)] | [Risk [removed: Factors](#sB7A45A12C24CD940C931B512B19484BB)] [added: Factors](#s90E7A4539EE0A80EE7AB201709F0C16A)] | [removed: [32](#sB7A45A12C24CD940C931B512B19484BB)] [added: [29](#s90E7A4539EE0A80EE7AB201709F0C16A)] |

| [Item [removed: 1B.](#s0385BCC5E1B9C0B157E0B512B1B42919)] [added: 1B.](#s459292DC67BAB8AD22CE20170A131520)] | [Unresolved Staff [removed: Comments](#s0385BCC5E1B9C0B157E0B512B1B42919)] [added: Comments](#s459292DC67BAB8AD22CE20170A131520)] | [removed: [43](#s0385BCC5E1B9C0B157E0B512B1B42919)] [added: [41](#s459292DC67BAB8AD22CE20170A131520)] |

| [Item [removed: 2.](#sC687E45A6F2B9BCD0321B512B1E5BCA7)] [added: 2.](#sE99905CC2A8A59ED6CF420170A439E17)] | [removed: [Properties](#sC687E45A6F2B9BCD0321B512B1E5BCA7)] [added: [Properties](#sE99905CC2A8A59ED6CF420170A439E17)] | [removed: [44](#sC687E45A6F2B9BCD0321B512B1E5BCA7)] [added: [42](#sE99905CC2A8A59ED6CF420170A439E17)] |

| [Item [removed: 3.](#sBEC0910FD4B23026A848B512B2074C81)] [added: 3.](#sB414B36729A55C04B2F520170A6D251B)] | [Legal [removed: Proceedings](#sBEC0910FD4B23026A848B512B2074C81)] [added: Proceedings](#sB414B36729A55C04B2F520170A6D251B)] | [removed: [45](#sBEC0910FD4B23026A848B512B2074C81)] [added: [43](#sB414B36729A55C04B2F520170A6D251B)] |

| [Item [removed: 4.](#s873CCF7CF63944374399B512B238B973)] [added: 4.](#s299375A7363816F4ECE220170A9725A2)] | [Mine Safety [removed: Disclosures](#s873CCF7CF63944374399B512B238B973)] [added: Disclosures](#s299375A7363816F4ECE220170A9725A2)] | [removed: [45](#s873CCF7CF63944374399B512B238B973)] [added: [43](#s299375A7363816F4ECE220170A9725A2)] |

| [Item [removed: 5.](#s20BFD3EA5B810DB0EDBDB512946DF050)] [added: 5.](#s1FB62878215C3C11095820166D62D73E)] | [Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity [removed: Securities](#s20BFD3EA5B810DB0EDBDB512946DF050)] [added: Securities](#s1FB62878215C3C11095820166D62D73E)] | [removed: [46](#s20BFD3EA5B810DB0EDBDB512946DF050)] [added: [44](#s1FB62878215C3C11095820166D62D73E)] |

| [Item [removed: 6.](#s85C4959389BAE93A2BADB5129E5FAA23)] [added: 6.](#sE2566B25C7513ED764422016879AF322)] | [Selected Financial [removed: Data](#s85C4959389BAE93A2BADB5129E5FAA23)] [added: Data](#sE2566B25C7513ED764422016879AF322)] | [removed: [48](#s85C4959389BAE93A2BADB5129E5FAA23)] [added: [46](#sE2566B25C7513ED764422016879AF322)] |

| [Item [removed: 7.](#s362F9929E4D04E9C8998B5129FD6EC34)] [added: 7.](#s092A7CD20543F5F4464620170B3E42DC)] | [Management’s Discussion and Analysis of Financial Condition and Results of [removed: Operations](#s362F9929E4D04E9C8998B5129FD6EC34)] [added: Operations](#s092A7CD20543F5F4464620170B3E42DC)] | [removed: [50](#s362F9929E4D04E9C8998B5129FD6EC34)] [added: [48](#s092A7CD20543F5F4464620170B3E42DC)] |

| [Item [removed: 7A.](#sE3382155A37CE1C4B200B512B6413B7F)] [added: 7A.](#sCC38D2DD8152CA3D1F0820170F470F15)] | [Quantitative and Qualitative Disclosures About Market [removed: Risk](#sE3382155A37CE1C4B200B512B6413B7F)] [added: Risk](#sCC38D2DD8152CA3D1F0820170F470F15)] | [removed: [81](#sE3382155A37CE1C4B200B512B6413B7F)] [added: [79](#sCC38D2DD8152CA3D1F0820170F470F15)] |

| [Item [removed: 8.](#s81FA614DD88CE6C8E7D8B512B673F865)] [added: 8.](#sCA88A35D47BB55E1ECEC20170F7AC1AC)] | [Financial Statements and Supplementary [removed: Data](#s81FA614DD88CE6C8E7D8B512B673F865)] [added: Data](#sCA88A35D47BB55E1ECEC20170F7AC1AC)] | [removed: [83](#s81FA614DD88CE6C8E7D8B512B673F865)] [added: [81](#sCA88A35D47BB55E1ECEC20170F7AC1AC)] |

| [Item [removed: 9.](#s3911AF88B9C9E495C2DAB512B69486B0)] [added: 9.](#sA3D5CDED4B09A0FC8BBA20170FABF364)] | [Changes in and Disagreements with Accountants on Accounting and Financial [removed: Disclosure](#s3911AF88B9C9E495C2DAB512B69486B0)] [added: Disclosure](#sA3D5CDED4B09A0FC8BBA20170FABF364)] | [removed: [83](#s3911AF88B9C9E495C2DAB512B69486B0)] [added: [81](#sA3D5CDED4B09A0FC8BBA20170FABF364)] |

| [Item [removed: 9A.](#sDC1FCBC3C831A9733142B512B6C6F1D9)] [added: 9A.](#sDAC09AD994C658BE6C7720170FD43091)] | [Controls and [removed: Procedures](#sDC1FCBC3C831A9733142B512B6C6F1D9)] [added: Procedures](#sDAC09AD994C658BE6C7720170FD43091)] | [removed: [84](#sDC1FCBC3C831A9733142B512B6C6F1D9)] [added: [82](#sDAC09AD994C658BE6C7720170FD43091)] |

| [Item [removed: 9B.](#s9A1F6C3CE62A468AB47DB512B6E8AB5D)] [added: 9B.](#sEBCFB87E1B7347D332B12017100385C2)] | [Other [removed: Information](#s9A1F6C3CE62A468AB47DB512B6E8AB5D)] [added: Information](#sEBCFB87E1B7347D332B12017100385C2)] | [removed: [84](#s9A1F6C3CE62A468AB47DB512B6E8AB5D)] [added: [82](#sEBCFB87E1B7347D332B12017100385C2)] |

| [PART [removed: III](#s8BB64F87AB14E13A6619B512B71A9914)] [added: III](#s53D5B6A6A920BFE6A4B820171021D52E)] | | |

| [Item [removed: 10.](#s4B0D7A20CE44B30FB528B512B73BB67A)] [added: 10.](#sFE0120AC1BF11EBFB1D720171041948D)] | [Directors, Executive Officers and Corporate [removed: Governance](#s4B0D7A20CE44B30FB528B512B73BB67A)] [added: Governance](#sFE0120AC1BF11EBFB1D720171041948D)] | [removed: [86](#s4B0D7A20CE44B30FB528B512B73BB67A)] [added: [83](#sFE0120AC1BF11EBFB1D720171041948D)] |

| [Item [removed: 11.](#s618E8C79488147527486B512B76DAD39)] [added: 11.](#s6BC898E23C7A3A6E571520171075F6CE)] | [Executive [removed: Compensation](#s618E8C79488147527486B512B76DAD39)] [added: Compensation](#s6BC898E23C7A3A6E571520171075F6CE)] | [removed: [86](#s618E8C79488147527486B512B76DAD39)] [added: [83](#s6BC898E23C7A3A6E571520171075F6CE)] |

| [Item [removed: 12.](#s83AD573B8DDA064779F5B512B78E1769)] [added: 12.](#sD9DA93C4FDFEA74630AB201710A8E79C)] | [Security Ownership of Certain Beneficial Owners and Management and Related Stockholder [removed: Matters](#s83AD573B8DDA064779F5B512B78E1769)] [added: Matters](#sD9DA93C4FDFEA74630AB201710A8E79C)] | [removed: [86](#s83AD573B8DDA064779F5B512B78E1769)] [added: [83](#sD9DA93C4FDFEA74630AB201710A8E79C)] |

| [Item [removed: 13.](#s6031CF6B6738C619B0B5B512B7C09D40)] [added: 13.](#s29759CFD2E1B09023D91201710C74D49)] | [Certain Relationships and Related Transactions, and Director [removed: Independence](#s6031CF6B6738C619B0B5B512B7C09D40)] [added: Independence](#s29759CFD2E1B09023D91201710C74D49)] | [removed: [86](#s6031CF6B6738C619B0B5B512B7C09D40)] [added: [83](#s29759CFD2E1B09023D91201710C74D49)] |

| [Item [removed: 14.](#s5B43FC771D1AF56BFFCAB512B7E2965A)] [added: 14.](#sBFB944790805D270C329201710F0DD8A)] | [Principal Accounting Fees and [removed: Services](#s5B43FC771D1AF56BFFCAB512B7E2965A)] [added: Services](#sBFB944790805D270C329201710F0DD8A)] | [removed: [86](#s5B43FC771D1AF56BFFCAB512B7E2965A)] [added: [83](#sBFB944790805D270C329201710F0DD8A)] |

| [Item [removed: 15.](#s61A2ACAD8E05C408D812B512B835B78D)] [added: 15.](#sC102002B827A94949B9E2017113C4204)] | [Exhibits and Financial Statement [removed: Schedules](#s61A2ACAD8E05C408D812B512B835B78D)] [added: Schedules](#sC102002B827A94949B9E2017113C4204)] | [removed: [87](#s61A2ACAD8E05C408D812B512B835B78D)] [added: [84](#sC102002B827A94949B9E2017113C4204)] |

| [Consolidated Financial [removed: Statements](#s92F0200CF9E772AC898DB512B8897B88)] [added: Statements](#s1678D8538B3524784B01201711953BED)] | | [F- [removed: 1](#s92F0200CF9E772AC898DB512B8897B88)] [added: 1](#s1678D8538B3524784B01201711953BED)] |

| [Exhibit [removed: Index](#sC7CE2221B2FBA0FCC50DB512BFE57186)] [added: Index](#s391239CD1182CE997E4420171877994D)] | | [A- [removed: 1](#sC7CE2221B2FBA0FCC50DB512BFE57186)] [added: 1](#s391239CD1182CE997E4420171877994D)] |

These forward-looking statements involve risks and uncertainties, including those that are described in the “Risk Factors” section of this [removed: report,] [added: report] and elsewhere in this [removed: report] [added: report,] that could cause actual results to differ materially from those reflected in such statements.

[removed: Throughout this report,] [added: | • |] “Biogen,” the [removed: “Company,”] [added: “company,”] “we,” “us” and “our” refer to Biogen Inc. [removed: (formerly Biogen Idec Inc.)] and its consolidated [removed: subsidiaries.][added: subsidiaries; |]

[removed: References to “RITUXAN” refer to both RITUXAN (the trade name for rituximab in the U.S., Canada and Japan) and MabThera (the trade name for rituximab outside the U.S., Canada and Japan), and] [added: | • |] “ANGIOMAX” refers to both ANGIOMAX (the trade name for bivalirudin in the U.S., Canada and Latin America) and ANGIOX (the trade name for bivalirudin in Europe). [added: |]

[removed: ALPROLIX®,] AVONEX®, BENEPALI®, [removed: ELOCTATE®,] FLIXABI®, PLEGRIDY®, RITUXAN®, [removed: TECFIDERA® and] [added: TECFIDERA®,] TYSABRI® [added: and ZINBRYTA®] are registered trademarks of Biogen.

FUMADERMTM and [removed: ZINBRYTATM] [added: SPINRAZATM] are trademarks of Biogen.

[removed: Other] [added: ALPROLIX®, ELOCTATE®, ENBREL®, FAMPYRATM, GAZYVA®, HUMIRA®, OCREVUS®, REMICADE® and other] trademarks referenced in this report are the property of their respective owners.

10-K 1 biib-20161231x10k.htm 10-K

| [PART I](#sF71E46622967387263112017077D85D1) | | |

| [PART II](#s6CFA95DBDE82A948202220170AB9A0CD) | | |

| [PART IV](#sFC458658BCC73B87EBF3201711199A3B) | | |

| [Signatures](#s2BF353079D72E44786832017116E7926) | | [85](#s2BF353079D72E44786832017116E7926) |

| • | the spin off of our hemophilia business, including its anticipated benefits, costs and tax treatment; |

| • | the anticipated amount and timing of payments under the Settlement and License Agreement with Forward Pharma A/S (Forward Pharma) and the timing, outcome and impact of administrative, regulatory, legal and other proceedings related to our patents and other proprietary intellectual property rights under our agreement with Forward Pharma; |

| • | potential costs and expenses incurred in connection with corporate restructurings and to execute business transformation and optimization initiatives; |

| • | the expected financial impact of ceasing manufacturing activities and vacating our biologics manufacturing facility in Cambridge, MA and warehouse space in Somerville, MA; |

| • | the potential impact on our results of operations and liquidity of the United Kingdom's (U.K.'s) intent to voluntarily depart from the European Union (E.U.); |

| | |

| --- | --- |

| | |

| --- | --- |

| | |

| --- | --- |

| | |

| --- | --- |

References in this report to:

| | |

| --- | --- |

| | |

| --- | --- |

| • | “RITUXAN” refers to both RITUXAN (the trade name for rituximab in the U.S., Canada and Japan) and MabThera (the trade name for rituximab outside the U.S., Canada and Japan); |

| | |

| --- | --- |

| • | "ELOCTATE" refers to both ELOCTATE (the trade name for Antihemophilic Factor (Recombinant), Fc Fusion Protein in the U.S., Canada and Japan) and ELOCTA (the trade name for Antihemophilic Factor (Recombinant), Fc Fusion Protein in the E.U.); and |

| | |

| --- | --- |

10-K 1 biib-20151231x10k.htm 10-K

| [PART I](#s1FF29E08DDAF0F7C756BB512B13F13FE) | | |

| [PART II](#s3D24CA0B08FF4F441AECB512B25A6EB0) | | |

| [PART IV](#sC9ADA8D49A749C17E525B512B814F67B) | | |

| [Signatures](#sAB131B415CFDEFD36707B512B8672AA5) | | [88](#sAB131B415CFDEFD36707B512B8672AA5) |

| • | the anticipated benefits, cost savings, and charges related to our corporate restructuring initiatives; |

Below is a summary of our owned and leased properties as of December 31, [removed: 2015.][added: 2016.]

In addition, we lease a total of approximately [removed: 1,312,000] [added: 1,250,000] square feet in Massachusetts, which is summarized as follows:

| • | [removed: 909,000] [added: 893,000] square feet in Cambridge, Massachusetts, which is comprised of a 67,000 square foot biologics manufacturing [removed: facility] [added: facility, which is subleased by Brammer,] and [removed: 842,000] [added: 826,000] square feet for our corporate headquarters, laboratory and additional office space; [added: and] |

| • | 357,000 square feet of office space in Weston, Massachusetts, of which 175,000 square feet has been subleased through the remaining term of our lease [removed: agreement; and] [added: agreement.] |

In addition, we lease 188,000 square feet of a facility in RTP, North Carolina from Eisai to manufacture our and Eisai's oral solid dose products and [removed: 10,000] [added: 40,000] square feet of warehouse space in Durham, North Carolina.

| • | 47,000 square feet of administrative [removed: space; and] [added: space.] |

| • | 50,000 square feet related to a laboratory [removed: facility.] [added: facility; and] |

In December [removed: 2015,] [added: 2015] we acquired land in Solothurn, [removed: Switzerland,] [added: Switzerland] where we [removed: plan to build] [added: are building] a biologics manufacturing facility in the Commune of Luterbach over the next several years.

We lease office space in Zug, Switzerland, our international headquarters, the [removed: United Kingdom,] [added: U.K.,] Germany, France, [removed: Denmark,] [added: Denmark] and numerous other countries.

Our international lease agreements expire at various dates through the year [removed: 2023.][added: 2028.]

| | |

| --- | --- |

| • | 46,000 square feet of warehouse space in Somerville, Massachusetts. |

Our common stock trades on The NASDAQ Global Select Market under the symbol “BIIB.” The following table shows the high and low sales price for our common stock as reported by The NASDAQ Global Select Market for each quarter in the years ended December 31, [removed: 2015] [added: 2016] and [removed: 2014:][added: 2015:]

| First Quarter | $ | [removed: 480.18] [added: 301.02] | | | $ | [removed: 334.40] [added: 242.07] | | | $ | [removed: 358.89] [added: 480.18] | | | $ | [removed: 270.62] [added: 334.40] | |

| Second Quarter | $ | [removed: 432.88] [added: 292.69] | | | $ | [removed: 368.88] [added: 223.02] | | | $ | [removed: 322.25] [added: 432.88] | | | $ | [removed: 272.02] [added: 368.88] | |

| Third Quarter | $ | [removed: 412.24] [added: 333.65] | | | $ | [removed: 265.00] [added: 240.07] | | | $ | [removed: 349.00] [added: 412.24] | | | $ | [removed: 298.31] [added: 265.00] | |

| Fourth Quarter | $ | [removed: 311.65] [added: 329.83] | | | $ | [removed: 254.00] [added: 268.00] | | | $ | [removed: 361.93] [added: 311.65] | | | $ | [removed: 290.85] [added: 254.00] | |

As of January [removed: 29, 2016,] [added: 27, 2017,] there were approximately [removed: 742] [added: 700] stockholders of record of our common stock.

While we historically have not paid cash dividends and do not have a current intention to pay cash dividends, we continually review our capital allocation strategies, including, among other things, payment of cash dividends, stock [removed: repurchases,] [added: repurchases] or acquisitions.

In [removed: May 2015,] [added: July 2016] our Board of Directors authorized a program to repurchase up to $5.0 billion of our common stock [removed: (2015] [added: (2016] Share Repurchase Program).

The following table summarizes our common stock repurchase activity under our [removed: 2015] [added: 2016] Share Repurchase Program during the fourth quarter of [removed: 2015:][added: 2016:]

As of December 31, [removed: 2015, the 2015 Share Repurchase Program was completed and] [added: 2016,] we repurchased and retired approximately [removed: 16.8] [added: 3.3] million shares of common stock at a cost of [removed: $5.0] [added: $1.0] billion [removed: during] [added: under] the [removed: year ended December 31, 2015.][added: 2016 Share Repurchase Program.]

In February [removed: 2011,] [added: 2011] our Board of Directors authorized a program to repurchase up to 20.0 million shares of our common stock (2011 Share Repurchase Program), which has been used principally to offset common stock issuances under our share-based compensation plans.

We did not repurchase any shares of common stock under our 2011 Share Repurchase Program during the year ended December 31, [removed: 2015] [added: 2016,] and have approximately 1.3 million shares remaining available for repurchase under this authorization.

The graph below compares the five-year cumulative total stockholder return on our common stock, the S&P 500 Index, the Nasdaq Pharmaceutical Index and the Nasdaq Biotechnology Index assuming the investment of $100.00 on December 31, [removed: 2010] [added: 2011] with dividends being reinvested.

[removed: ][added: ]

| | [removed: 2010 | |] 2011 | | 2012 | | 2013 | | 2014 | | 2015 | | [added: 2016 | |]

| | 2016 | | | | | | | | 2015 | | | | | | |

This authorization does not have an expiration date.

Repurchased shares will be retired.

| October 2016 | 1,254,818 | | | 298.71 | | | 1,254,818 | | | $ | 4,276.3 | |

| November 2016 | 939,046 | | | 294.24 | | | 939,046 | | | $ | 4,000.0 | |

| December 2016 | — | | | — | | | — | | | $ | 4,000.0 | |

| Total | 2,193,864 | | | 296.80 | | | | | | | | |

| Biogen Inc. | 100.00 | | 133.00 | | 254.04 | | 308.45 | | 278.37 | | 257.68 | |

| NASDAQ Pharmaceutical | 100.00 | | 114.32 | | 155.11 | | 188.95 | | 199.22 | | 197.05 | |

| S&P 500 Index | 100.00 | | 116.00 | | 153.57 | | 174.60 | | 177.01 | | 198.18 | |

| NASDAQ Biotechnology | 100.00 | | 132.74 | | 220.37 | | 296.19 | | 331.05 | | 260.37 | |

| | 2015 | | | | | | | | 2014 | | | | | | |

| October 2015 | 4,976,270 | | | 275.87 | | | 4,976,270 | | | $ | 629.0 | |

| November 2015 | 2,131,417 | | | 295.12 | | | 2,131,417 | | | $ | — | |

| December 2015 | — | | | — | | | — | | | $ | — | |

| Total | 7,107,687 | | | 281.64 | | | | | | | | |

| Biogen Inc. | 100.00 | | 164.13 | | 218.30 | | 416.96 | | 506.26 | | 456.90 | |

| NASDAQ Pharmaceutical | 100.00 | | 107.59 | | 123.00 | | 166.89 | | 203.30 | | 214.35 | |

| S&P 500 Index | 100.00 | | 102.11 | | 118.45 | | 156.82 | | 178.28 | | 180.75 | |

| NASDAQ Biotechnology | 100.00 | | 112.09 | | 148.78 | | 247.01 | | 331.99 | | 371.06 | |

| | [removed: 2015] [added: 2016] | | | | [removed: 2014] [added: 2015] | | | | [removed: 2013] [added: 2014] | | | | [removed: 2012] [added: 2013] | | | | [removed: 2011] [added: 2012] | | |

| (In millions, except per share amounts) | [removed: (3) (4)] [added: (d) (e)] | | | | [added: (d)] | | | | [removed: (1) (2)] [added: (f)] | | | | [added: (g)] | | | | [removed: (1)] [added: (h)] | | |

| Product revenues, net [added: (a)] | $ | [removed: 9,188.5] [added: 9,817.9] | | | $ | [removed: 8,203.4] [added: 9,188.5] | | | $ | [removed: 5,542.3] [added: 8,203.4] | | | $ | [removed: 4,166.1] [added: 5,542.3] | | | $ | [removed: 3,836.1] [added: 4,166.1] | |

| Revenues from [removed: unconsolidated joint business] [added: anti-CD20 therapeutic programs] | [removed: 1,339.2] [added: 1,314.5] | | | | [removed: 1,195.4] [added: 1,339.2] | | | | [removed: 1,126.0] [added: 1,195.4] | | | | [removed: 1,137.9] [added: 1,126.0] | | | | [removed: 996.6] [added: 1,137.9] | | |

| Other revenues | [removed: 236.1] [added: 316.4] | | | | [removed: 304.5] [added: 236.1] | | | | [removed: 263.9] [added: 304.5] | | | | [removed: 212.5] [added: 263.9] | | | | [removed: 215.9] [added: 212.5] | | |

| Total revenues | [removed: 10,763.8] [added: 11,448.8] | | | | [removed: 9,703.3] [added: 10,763.8] | | | | [removed: 6,932.2] [added: 9,703.3] | | | | [removed: 5,516.5] [added: 6,932.2] | | | | [removed: 5,048.6] [added: 5,516.5] | | |

| Total cost and expenses | [removed: 5,872.8] [added: 6,298.4] | | | | [removed: 5,747.7] [added: 5,872.8] | | | | [removed: 4,441.6] [added: 5,747.7] | | | | [removed: 3,707.4] [added: 4,441.6] | | | | [removed: 3,323.9] [added: 3,707.4] | | |

| Gain on sale of rights | — | | | | [removed: 16.8] [added: —] | | | | [removed: 24.9] [added: 16.8] | | | | [removed: 46.8] [added: 24.9] | | | | [removed: —] [added: 46.8] | | |

| Income from operations | [removed: 4,891.0] [added: 5,150.4] | | | | [removed: 3,972.4] [added: 4,891.0] | | | | [removed: 2,515.5] [added: 3,972.4] | | | | [removed: 1,855.9] [added: 2,515.5] | | | | [removed: 1,724.7] [added: 1,855.9] | | |

| Other income (expense), net | [removed: (123.7] [added: (217.4] | | ) | | [removed: (25.8] [added: (123.7] | | ) | | [removed: (34.9] [added: (25.8] | | ) | | [removed: (0.7] [added: (34.9] | | ) | | [removed: (13.5] [added: (0.7] | | ) |

| Income before income tax expense and equity in loss of investee, net of tax | [removed: 4,767.3] [added: 4,933.0] | | | | [removed: 3,946.6] [added: 4,767.3] | | | | [removed: 2,480.6] [added: 3,946.6] | | | | [removed: 1,855.1] [added: 2,480.6] | | | | [removed: 1,711.2] [added: 1,855.1] | | |

| Income tax expense | [removed: 1,161.6] [added: 1,237.3] | | | | [removed: 989.9] [added: 1,161.6] | | | | [removed: 601.0] [added: 989.9] | | | | [removed: 470.6] [added: 601.0] | | | | [removed: 444.5] [added: 470.6] | | |

| Equity in loss of investee, net of tax | [removed: 12.5] [added: —] | | | | [removed: 15.1] [added: 12.5] | | | | [removed: 17.2] [added: 15.1] | | | | [removed: 4.5] [added: 17.2] | | | | [removed: —] [added: 4.5] | | |

| Net income | [removed: 3,593.2] [added: 3,695.7] | | | | [removed: 2,941.6] [added: 3,593.2] | | | | [removed: 1,862.3] [added: 2,941.6] | | | | [removed: 1,380.0] [added: 1,862.3] | | | | [removed: 1,266.7] [added: 1,380.0] | | |

| Net income (loss) attributable to noncontrolling interests, net of tax | [removed: 46.2] [added: (7.1] | | [added: )] | | [removed: 6.8] [added: 46.2] | | | | [removed: —] [added: 6.8] | | | | — | | | | [removed: 32.3] [added: —] | | |

| Net income attributable to Biogen Inc. | $ | [removed: 3,547.0] [added: 3,702.8] | | | $ | [removed: 2,934.8] [added: 3,547.0] | | | $ | [removed: 1,862.3] [added: 2,934.8] | | | $ | [removed: 1,380.0] [added: 1,862.3] | | | $ | [removed: 1,234.4] [added: 1,380.0] | |

| Diluted earnings per share attributable to Biogen Inc. | $ | [removed: 15.34] [added: 16.93] | | | $ | [removed: 12.37] [added: 15.34] | | | $ | [removed: 7.81] [added: 12.37] | | | $ | [removed: 5.76] [added: 7.81] | | | $ | [removed: 5.04] [added: 5.76] | |

| Weighted-average shares used in calculating diluted earnings per share attributable to Biogen Inc. | [removed: 231.2] [added: 218.8] | | | | [removed: 237.2] [added: 231.2] | | | | [removed: 238.3] [added: 237.2] | | | | [removed: 239.7] [added: 238.3] | | | | [removed: 245.0] [added: 239.7] | | |

| (In millions) | [removed: (5) (6)] | | | | | | | | | | | | | | | | | | |

| Cash, cash equivalents and marketable securities | $ | [removed: 6,188.9] [added: 7,724.5] | | | $ | [removed: 3,316.0] [added: 6,188.9] | | | $ | [removed: 1,848.5] [added: 3,316.0] | | | $ | [removed: 3,742.4] [added: 1,848.5] | | | $ | [removed: 3,107.4] [added: 3,742.4] | |

| Total assets | $ | [removed: 19,504.8] [added: 22,876.8] | | | $ | [removed: 14,314.7] [added: 19,504.8] | | | $ | [removed: 11,863.3] [added: 14,314.7] | | | $ | [removed: 10,130.1] [added: 11,863.3] | | | $ | [removed: 9,049.6] [added: 10,130.1] | |

| Notes [removed: payable, line of credit] [added: payable] and other financing arrangements, less current portion [added: (b)] | $ | [removed: 6,521.5] [added: 6,512.7] | | | $ | [removed: 580.3] [added: 6,521.5] | | | $ | [removed: 592.4] [added: 580.3] | | | $ | [removed: 687.4] [added: 592.4] | | | $ | [removed: 1,060.8] [added: 687.4] | |

| Total Biogen Inc. shareholders’ equity [added: (c)] | $ | [removed: 9,372.8] [added: 12,140.1] | | | $ | [removed: 10,809.0] [added: 9,372.8] | | | $ | [removed: 8,620.2] [added: 10,809.0] | | | $ | [removed: 6,961.5] [added: 8,620.2] | | | $ | [removed: 6,425.5] [added: 6,961.5] | |

| [removed: (1)] [added: (g)] | Our share of revenues from [removed: unconsolidated joint business] [added: anti-CD20 therapeutic programs] reflects charges of [removed: $50.0 million in 2011 and] $49.7 million in 2013 for damages and interest awarded to Hoechst in Genentech's arbitration with Hoechst for RITUXAN. |

| [removed: (2)] [added: (h)] | Commencing in the second quarter of [removed: 2013,] [added: 2013] product and total revenues include 100% of net revenues related to sales of TYSABRI as a result of our acquisition of all remaining rights to TYSABRI from Elan Pharma International, Ltd (Elan), an affiliate of Elan Corporation, plc. Upon the closing, our collaboration agreement was terminated, and we no longer record collaboration profit sharing expense. We recognized collaboration profit sharing expense of $85.4 [removed: million, $317.9] million and [removed: $317.8] [added: $317.9] million during the years ended December 31, [removed: 2013, 2012] [added: 2013] and [removed: 2011,] [added: 2012,] respectively. [removed: In addition, product and total revenues includes net revenues related to sales of TECFIDERA.] |

| [removed: (5)] [added: (b)] | Notes [removed: payable, line of credit] [added: payable] and other financing [removed: arrangements, less current portion] [added: arrangements] reflects the issuance of our senior unsecured notes for an aggregate principal amount of $6.0 billion [removed: on] [added: in] September [removed: 15, 2015.] [added: 2015, and the 2013 repayment of our 6.0% notes that were issued in 2008 for an aggregate principal amount of $450.0 million.] |

| Our results of operations are summarized as follows: | | | | | | | | | | | | | | | | | | | |

| Our financial condition is summarized as follows: | | | | | | | | | | | | | | | | | | | |

| | 2016 | | | | 2015 | | | | 2014 | | | | 2013 | | | | 2012 | | |

| (a) | Product revenues, net reflect the impact of the following product launches: |

| • | Commercial sales of SPINRAZA began in the fourth quarter of 2016. |

| • | Under the terms of our collaboration agreement with AbbVie, we began to recognize revenues on sales of ZINBRYTA to third parties in the E.U. in the third quarter of 2016. |

| • | Under the terms of our commercial agreement with Samsung Bioepis, we began to recognize revenues on sales of BENEPALI and FLIXABI to third parties in the E.U. in the first quarter of 2016 and third quarter of 2016, respectively. |

| • | Commercial sales of ALPROLIX commenced in the second quarter of 2014 and commercial sales of ELOCTATE and PLEGRIDY commenced in the third quarter of 2014. |

| • | TECFIDERA began in April 2013. |

| | |

| --- | --- |

| | |

| --- | --- |

| (c) | Total Biogen Inc.'s shareholders' equity reflects the repurchase of approximately 32.8 million shares of our common stock at a cost of approximately $8.3 billion between 2012 and 2016: |

| | |

| --- | --- |

| • | During 2016 we repurchased and retired approximately 3.3 million shares of our common stock at a cost of $1.0 billion under our 2016 Share Repurchase Program. |

| | |

| --- | --- |

| • | During 2015 we repurchased and retired approximately 16.8 million shares of our common stock at a cost of $5.0 billion under our 2015 Share Repurchase Program. |

| | |

| --- | --- |

| • | During 2014, 2013 and 2012 we repurchased approximately 2.9 million, 2.0 million and 7.8 million shares, respectively of our common stock at a cost of approximately $2.3 billion under our 2011 Share Repurchase Program of which approximately 3.7 million of these shares were retired. |

| | |

| --- | --- |

| (d) | Total cost and expenses for the years ended December 31, 2016 and 2015, include restructuring charges of $33.1 million and $93.4 million, respectively. In addition, total cost and expenses for the year ended December 31, 2016, also include charges to cost of sales totaling $52.4 million of expenses incurred as a result of our determination to vacate and cease manufacturing in our small-scale biologics facility in Cambridge, MA as well as vacate our warehouse in Somerville, MA. Total cost and expenses for year ended December 31, 2016, also include $18.1 million of costs incurred directly related to our separation of our hemophilia business into an independent, publicly traded company. |

| | |

| --- | --- |

| (e) | Total cost and expenses for the year ended December 31, 2016, includes a pre-tax charge of $454.8 million related to the January 2017 settlement and license agreement with Forward Pharma A/S (Forward Pharma). |

| | |

| --- | --- |

| (f) | In June 2014 AIFA approved a resolution affirming that there is no reimbursement limit from and after February 2013. As a result, we recognized $53.5 million of TYSABRI revenues in the second quarter of 2014 related to the periods beginning February 2013 that were previously deferred. |

| | |

| --- | --- |

| | |

| --- | --- |

| (3) | Other revenues reflects a decrease in royalty revenues due to the December 2014 expiration of U.S. patent rights that gave rise to royalty payments related to ANGIOMAX. |

| (4) | Included in total cost and expenses is a restructuring charge of $93.4 million incurred in connection with our corporate restructuring announced on October 21, 2015, which included the termination of certain pipeline programs and an 11% reduction in workforce. |

| (6) | Biogen Inc.'s shareholders' equity reflects a reduction in additional paid in capital and retained earnings totaling $5.0 billion resulting from the repurchase and retirement of our common stock under our 2015 Share Repurchase Program. |

The information required by this Item 8 is contained on pages F-1 through [removed: F-71] [added: F-75] of this report and is incorporated herein by reference.

We have carried out an evaluation, under the supervision and with the participation of our management, including our principal executive officer and principal financial officer, of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended), as of December 31, [removed: 2015.][added: 2016.]

There were no changes in our internal control over financial reporting during the quarter ended December 31, [removed: 2015] [added: 2016] that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Our management assessed the effectiveness of our internal control over financial reporting as of December 31, [removed: 2015.][added: 2016.]

Based on our assessment, our management has concluded that, as of December 31, [removed: 2015,] [added: 2016,] our internal control over financial reporting is effective based on those criteria.

The effectiveness of our internal control over financial reporting as of December 31, [removed: 2015] [added: 2016] has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their attestation report, which is included herein.

The response to the remainder of this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Proposal 1 - Election of Directors,” “Corporate [removed: Governance,”] [added: Governance at Biogen,”] “Stock Ownership - Section 16(a) Beneficial Ownership Reporting Compliance” and “Miscellaneous - Stockholder Proposals” contained in the proxy statement for our [removed: 2016] [added: 2017] annual meeting of stockholders.

The response to this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Executive Compensation [removed: and Related Information”] [added: Matters”] and “Corporate [removed: Governance”] [added: Governance at Biogen”] contained in the proxy statement for our [removed: 2016] [added: 2017] annual meeting of stockholders.

The response to this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Stock Ownership” and “Equity Compensation Plan Information” contained in the proxy statement for our [removed: 2016] [added: 2017] annual meeting of stockholders.

The response to this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Certain Relationships and Related Person Transactions” and “Corporate [removed: Governance”] [added: Governance at Biogen”] contained in the proxy statement for our [removed: 2016] [added: 2017] annual meeting of stockholders.

The response to this item is incorporated by reference from the discussion responsive thereto in the section entitled “Proposal 2 — Ratification of the Selection of our Independent Registered Public Accounting Firm” contained in the proxy statement for our [removed: 2016] [added: 2017] annual meeting of stockholders.

| Report of Independent Registered Public Accounting Firm | | [removed: F-71] [added: F-75] |

Date: February [removed: 3, 2016][added: 2, 2017]

Pursuant to the requirements [added: of] the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

| /S/ [removed: GEORGE A. SCANGOS] [added: MICHEL VOUNATSOS] | | Director and Chief Executive Officer (principal executive officer) | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ PAUL J. CLANCY | | Executive Vice President, Finance and Chief Financial Officer (principal financial officer) | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ GREGORY F. COVINO | | Vice President, Finance, Chief Accounting Officer (principal accounting officer) | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ STELIOS PAPADOPOULOS | | Director and Chairman of the Board of Directors | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ ALEXANDER J. DENNER | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ CAROLINE D. DORSA | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ NANCY L. LEAMING | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ RICHARD C. MULLIGAN | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ ROBERT W. PANGIA | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ BRIAN S. POSNER | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ ERIC K. ROWINSKY | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ LYNN SCHENK | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| /S/ STEPHEN A. SHERWIN | | Director | | February [removed: 3, 2016] [added: 2, 2017] |

| | For the [removed: Years] [added: Year] Ended December 31, | | | [removed: | | | | | | | |]

| | [removed: 2015] [added: 2016] | | | | [removed: 2014] [added: 2015] | | | | [removed: 2013] [added: 2014] | | |

| Product, net | $ | [removed: 9,188.5] [added: 9,817.9] | | | $ | [removed: 8,203.4] [added: 9,188.5] | | | $ | [removed: 5,542.3] [added: 8,203.4] | |

| Other | [removed: 236.1] [added: 316.4] | | | | [removed: 304.5] [added: 236.1] | | | | [removed: 263.9] [added: 304.5] | | |

| Total revenues | [removed: 10,763.8] [added: 11,448.8] | | | | [removed: 9,703.3] [added: 10,763.8] | | | | [removed: 6,932.2] [added: 9,703.3] | | |

| Cost of sales, excluding amortization of acquired intangible assets | [removed: 1,240.4] [added: 1,478.7] | | | | [removed: 1,171.0] [added: 1,240.4] | | | | [removed: 857.7] [added: 1,171.0] | | |

| Research and development | [removed: 2,012.8] [added: 1,973.3] | | | | [removed: 1,893.4] [added: 2,012.8] | | | | [removed: 1,444.1] [added: 1,893.4] | | |

| Selling, general and administrative | [removed: 2,113.1] [added: 1,947.9] | | | | [removed: 2,232.3] [added: 2,113.1] | | | | [removed: 1,712.1] [added: 2,232.3] | | |

| Amortization of acquired intangible assets | [removed: 382.6] [added: 385.6] | | | | [removed: 489.8] [added: 382.6] | | | | [removed: 342.9] [added: 489.8] | | |

| Restructuring charges | [removed: 93.4] [added: 33.1] | | | | [removed: —] [added: 93.4] | | | | — | | |

| Collaboration profit [added: (loss)] sharing | [removed: —] [added: 10.2] | | | | — | | | | [removed: 85.4] [added: —] | | |

| [removed: (Gain) loss] [added: Loss (gain)] on fair value remeasurement of contingent consideration | [removed: 30.5] [added: 14.8] | | | | [removed: (38.9] [added: 30.5] | | [removed: )] | | [removed: (0.5] [added: (38.9] | | ) |

| Total cost and expenses | [removed: 5,872.8] [added: 6,298.4] | | | | [removed: 5,747.7] [added: 5,872.8] | | | | [removed: 4,441.6] [added: 5,747.7] | | |

| Gain on sale of rights | — | | | | [removed: 16.8] [added: —] | | | | [removed: 24.9] [added: 16.8] | | |

| Income from operations | [removed: 4,891.0] [added: 5,150.4] | | | | [removed: 3,972.4] [added: 4,891.0] | | | | [removed: 2,515.5] [added: 3,972.4] | | |

| Other income (expense), net | [removed: (123.7] [added: (217.4] | | ) | | [removed: (25.8] [added: (123.7] | | ) | | [removed: (34.9] [added: (25.8] | | ) |

| Income before income tax expense and equity in loss of investee, net of tax | [removed: 4,767.3] [added: 4,933.0] | | | | [removed: 3,946.6] [added: 4,767.3] | | | | [removed: 2,480.6] [added: 3,946.6] | | |

| Income tax expense | [removed: 1,161.6] [added: 1,237.3] | | | | [removed: 989.9] [added: 1,161.6] | | | | [removed: 601.0] [added: 989.9] | | |

| Equity in loss of investee, net of tax | [removed: 12.5] [added: —] | | | | [removed: 15.1] [added: 12.5] | | | | [removed: 17.2] [added: 15.1] | | |

| Net income | [removed: 3,593.2] [added: 3,695.7] | | | | [removed: 2,941.6] [added: 3,593.2] | | | | [removed: 1,862.3] [added: 2,941.6] | | |