Bioverativ (BIVV) 10-K 14 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 09, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Bioverativ Inc.
Entity Central Index Key	1,681,689
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 6,433.3
Entity Common Stock, Shares Outstanding		108,223,644
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Product, net	$ 1,089.1	$ 846.6	$ 554.1
Collaboration	79.4	40.8	6.2
Total revenues	1,168.5	887.4	560.3
Cost and expenses:
Cost of sales	279.6	237.9	52.9
Research and development	224.6	210.1	236.9
Selling, general and administrative	217.1	147	172.5
Total cost and expenses	721.3	595	462.3
Income from operations	447.2	292.4	98
Other income (expense), net	4.7	(0.5)	0.6
Income before income tax expense (benefit)	451.9	291.9	98.6
Income tax expense (benefit)	96.3	(147.7)	(10)
Net income	$ 355.6	$ 439.6	$ 108.6
Net income per share:
Basic earnings (in dollars per share)	$ 3.29	$ 4.07	$ 1.01
Diluted earnings (in dollars per share)	$ 3.28	$ 4.07	$ 1.01
Weighted average shares used in calculating:
Basic earnings per share (in shares)	108.1	108	108
Diluted earnings per share (in shares)	108.5	108	108
Other comprehensive income (loss):
Net income	$ 355.6	$ 439.6	$ 108.6
Currency translation adjustment	(1.8)	1.5	(0.2)
Total other comprehensive income (loss)	(1.8)	1.5	(0.2)
Comprehensive income	$ 353.8	$ 441.1	$ 108.4

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 436.5
Accounts receivable, net	189.4	$ 149.4
Inventory	40.6	302
Restricted cash	40
Other current assets	71.8	24.2
Total current assets	778.3	475.6
Property, plant and equipment, net	24	28.4
Intangible assets, net	635.9	51.7
Goodwill	170.7
Deferred tax assets	1	154.2
Other long-term assets	8.4	22
Total assets	1,618.3	731.9
Current liabilities:
Accounts payable	26.1	12.7
Accrued expenses and other current liabilities	233.5	89.3
Due to True North Therapeutics equityholders	40
Due to Biogen	90.5
Total current liabilities	390.1	102
Other long-term liabilities	92.5	63.7
Deferred tax liabilities, net	89
Contingent consideration	149.1
Total liabilities	720.7	165.7
Commitments and contingencies
Equity:
Preferred stock, $0.001 par value (shares authorized of 50,000,000 at December 31, 2017 and 0 at December 31, 2016; no shares issued and outstanding at December 31, 2017 or at December 31, 2016)
Common stock, $0.001 par value (shares authorized of 800,000,000 at December 31, 2017 and 1,000 at December 31, 2016; shares issued and outstanding of 108,203,439 at December 31, 2017 and 1,000 at December 31, 2016)	0.1
Additional paid-in capital	565.2
Retained earnings	332.3
Net parent company investment		564.4
Accumulated other comprehensive loss		1.8
Total equity	897.6	566.2
Total liabilities and equity	$ 1,618.3	$ 731.9

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	800,000,000	1,000
Common stock, shares issued	108,203,439	1,000
Common stock, shares outstanding	108,203,439	1,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 355.6	$ 439.6	$ 108.6
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	14.5	53.4	15.6
Stock-based compensation	32	15.3	13.2
Deferred taxes	(59.5)	(154.2)
Remeasurement of contingent consideration	9.9
Changes in operating assets and liabilities, net:
Accounts receivable	(39.9)	(55)	(27)
Inventory	82.4	(49.9)	(72.9)
Due from Biogen, net	90.5
Other assets	(45.6)	(22.6)	(5.4)
Accounts payable	11.1	2	(2.3)
Accrued expenses and other current liabilities	110.9	40	(2)
Other liabilities	28.8	33	13.6
Net cash flows provided by operating activities	590.7	301.6	41.4
Cash flows from investing activities:
Purchases of property, plant and equipment	(13.1)	(8.7)	(10.6)
Acquisition of True North Therapeutics, net of cash	(395.7)
Acquisition of intangible assets		(26.5)
Net cash flows used in investing activities	(408.8)	(35.2)	(10.6)
Cash flows from financing activities:
Transfers to Biogen	(45.3)	(266.4)	(30.8)
Cash from Biogen upon separation	325
Working capital adjustments paid to Biogen, net	(23.5)
Shares issued under employee benefit plans	(2.6)
Net cash flows provided by (used in) financing activities	253.6	$ (266.4)	$ (30.8)
Effect of foreign exchange rate changes on cash and equivalents	1
Net increase in cash and cash equivalents	436.5
Cash and cash equivalents, end of the year	436.5
Supplemental cash flow disclosure:
Cash paid for income taxes	$ 144.5

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Common Stock	Additional Paid-in Capital	Retained Earnings	Net Parent Company Investment	Accumulated Other Comprehensive Income	Total
Beginning Balance at Dec. 31, 2015				$ 384.4	$ 0.3	$ 384.7
Increase (decrease) in stockholders' equity
Net income				439.6		439.6
Transfers to Biogen				(259.6)		(259.6)
Foreign currency translation adjustments					1.5	1.5
Ending Balance at Dec. 31, 2016				564.4	1.8	$ 566.2
Ending Balance (in shares) at Dec. 31, 2016						1,000
Increase (decrease) in stockholders' equity
Net income			$ 332.3	23.3		$ 355.6
Separation-related adjustments		$ 2.1		(312.4)		(310.3)
Transfers to Biogen				(43)		(43)
Cash from Biogen				325		325
Working capital adjustments paid to Biogen, net				(23.5)		(23.5)
Reclassification of net parent company investment to additional paid-in capital		533.8		$ (533.8)
Issuance of common stock upon separation	$ 0.1	(0.1)
Issuance of common stock upon separation (in shares)	108,000,000
Share-based compensation expense		32				32
Shares issued under employee benefit plans		(2.6)				(2.6)
Shares issued under employee benefit plans (in shares)	200,000
Foreign currency translation adjustments					$ (1.8)	(1.8)
Ending Balance at Dec. 31, 2017	$ 0.1	$ 565.2	$ 332.3			$ 897.6
Ending Balance (in shares) at Dec. 31, 2017	108,200,000					108,203,439

Nature of Business and Basis of

Nature of Business and Basis of Preparation	12 Months Ended
	Dec. 31, 2017
Nature of Business and Basis of Preparation
Nature of Business and Basis of Preparation	1. Nature of Business and Basis of Preparation Nature of Business Bioverativ Inc. (Bioverativ) separated from Biogen Inc. (Biogen) on February 1, 2017 as a result of a special dividend distribution of all the outstanding shares of common stock of Bioverativ to Biogen stockholders. The distribution was made to Biogen stockholders of record as of the close of business on January 17, 2017, who received one share of Bioverativ common stock for every two shares of Biogen common stock held as of such date. As a result of the distribution, Bioverativ is now an independent public company. Bioverativ holds the assets and liabilities of Biogen’s former hemophilia business. Bioverativ is focused on the discovery, research, development and commercialization of innovative therapies for the treatment of hemophilia and other blood disorders. Bioverativ’s marketed products include ELOCTATE and ALPROLIX, extended half‑life factors for the treatment of hemophilia A and hemophilia B, respectively. Pursuant to a development and commercialization agreement, Bioverativ collaborates with Swedish Orphan Biovitrum AB (publ) (Sobi) to jointly develop and commercialize ELOCTATE and ALPROLIX globally. Sobi has responsibility for commercialization of ELOCTATE and ALPROLIX in Europe, Russia and certain countries in Northern Africa and the Middle East, while Bioverativ retains rights to commercialize those therapies in the United States, Japan, Canada, Australia, Latin American countries and all other markets excluding Sobi’s commercialization territory. See Note 4, Collaborations , for further information on Bioverativ’s collaboration with Sobi. On January 21, 2018, we entered into an Agreement and Plan of Merger (the “Merger Agreement”), with Sanofi (“Parent” or “Sanofi”), a French société anonyme, and Blink Acquisition Corp. (“Merger Sub”), a Delaware corporation and indirect wholly-owned subsidiary of Parent. See Note 21, Subsequent Events to our audited consolidated financial statements included in this Form 10-K. Basis of Preparation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (GAAP). The accompanying consolidated financial statements include those of the company and its subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We operate as one operating segment, which is discovering, researching, developing and commercializing innovative therapies for the treatment of hemophilia and other rare blood disorders. The accompanying consolidated financial statements reflect the consolidated financial position and consolidated results of operations of the company as an independent, publicly-traded company for the period after the February 1, 2017 separation. The consolidated financial statements also reflect the consolidated financial position and consolidated results of operations of the company as a consolidated reporting entity of Biogen for periods prior to the separation. In 2017, the company recorded certain separation related adjustments in its consolidated statement of equity. The separation related adjustments primarily related to differences between assets and liabilities transferred to Bioverativ as a result of the separation and assets and liabilities reported in the company’s consolidated balance sheet as of January 31, 2017. Separation related adjustments consists primarily of inventory and deferred tax assets retained by Biogen upon separation. Additional separation related adjustments could be recorded in future periods. Prior to the separation, the consolidated financial statements were prepared on a standalone basis and were derived from Biogen’s consolidated financial statements and accounting records as if the former hemophilia business of Biogen had been standalone business. Accordingly, financial information for periods prior to the separation is shown on a carve-out basis for the hemophilia business as part of Biogen. The consolidated financial statements reflected the company’s financial position, results of operations and cash flows as the business was operated as part of Biogen prior to the distribution. Prior to the separation, the consolidated financial statements included the attribution of certain assets and liabilities that were historically held at the Biogen corporate level but which were specifically identifiable or attributable to the company. All intercompany transactions and accounts within the company were eliminated. All transactions between the company and Biogen were considered to be effectively settled in the consolidated financial statements at the time the transaction was recorded. The total net effect of the settlement of the transactions with Biogen is reflected in the consolidated statements of cash flows in periods prior to the separation as a financing activity and in the consolidated balance sheet as net parent company investment. Prior to the separation, these consolidated financial statements include an allocation from Biogen to us for certain research and development and selling, general and administrative costs not directly attributable to the hemophilia business of Biogen. The research and development costs include depreciation and other facility‑based expenses, regulatory affairs function, pharmacovigilance, other infrastructure and management costs supporting multiple projects. The selling, general and administrative costs include certain services provided by Biogen, which include, but are not limited to, executive oversight, treasury, finance, legal, human resources, tax planning, internal audit, financial reporting, information technology, investor relations, shared services, insurance, employee benefits and incentives and share‑based compensation. Allocated amounts have been included in research and development, selling, general and administrative and other income and expense. These expenses have been allocated to the company based on direct usage or benefit where specifically identifiable, with the remainder allocated primarily based on hours or direct costs. The company considers the expense methodology and results to be reasonable for all periods presented. However, the allocations may not be indicative of the actual expense that would have been incurred had the company operated as an independent, publicly traded company for the periods presented. In periods prior to the separation, Bioverativ’s employees participated in various benefit and share-based compensation plans maintained by Biogen. A portion of the cost of those plans was included in the company’s financial statements. However, the consolidated balance sheets in periods prior to the separation did not include any equity related to share-based compensation plans. Prior to the separation, the company’s equity balance represented the excess of total assets over total liabilities, including the due to/from balances between the company and Biogen (net parent company investment) and cumulative translation adjustment. In connection with the separation, the company’s net parent company investment balance was reclassified to additional paid-in capital.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The accompanying consolidated financial statements reflect the application of certain significant accounting policies as described below and elsewhere in these notes to the consolidated financial statements. Reclassifications Certain prior year amounts have been reclassified for consistency with the current period presentation. These reclassifications had no effect on the reported results of operations. In first quarter of 2017, the company concluded that it was appropriate to classify costs associated with medical affairs as research and development to better align with Bioverativ’s organizational structure. Previously, such costs had been classified as selling, general and administrative. As a result, the amounts that were previously presented in selling, general and administrative were reclassified in research and development for the years ended December 31, 2016 and 2015. For the Years Ended December 31, (In millions) 2016 2015 Medical reclassification $ 31.2 $ 50.8 Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments, and assumptions that may affect the reported amounts of assets, liabilities, equity, revenues and expenses, and related disclosure of contingent assets and liabilities. On an on-going basis we evaluate our estimates, judgments and methodologies. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets, liabilities and equity and the amount of revenues and expenses. Actual results may differ from these estimates under different assumptions or conditions. Cash and Cash Equivalents We consider only those investments which are highly liquid, readily convertible to cash and that mature within three months from date of purchase to be cash equivalents. The carrying values of money market funds approximate fair value due to their short-term maturities. Accounts Receivable The majority of accounts receivable arise from product sales and primarily represent amounts due from specialty pharmacies, hemophilia treatment centers, public and private hospitals and independent specialty distributors as well as contract manufacturing and royalty revenue from Sobi. The company monitors the financial performance and creditworthiness of its customers so that the company can properly assess and respond to changes in their credit profile. The company provides reserves against trade receivables for estimated losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are charged or written‑off against the reserve. Concentration of Credit Risk CVS Health Corporation (CVS), a specialty pharmacy and ASD Specialty Healthcare (ASD), a specialty distributor, individually represent 13% and 12%, respectively, of outstanding accounts receivable for the year ended December 31, 2017; CVS, ASD and Accredo Health Incorporated, a specialty pharmacy, individually represent 24%, 14% and 11%, respectively, of outstanding accounts receivable for the year ended December 31, 2016. Other than these significant customers, concentration of credit risk with respect to receivables, which are typically unsecured, are largely mitigated due to the wide variety of customers. The majority of accounts receivable arise from product sales in the United States and Japan and have standard payment terms which generally require payment within 30 to 90 days. The company monitors the financial performance and creditworthiness of its customers so that the company can properly assess and respond to changes in their credit profile. The company continues to monitor these conditions and assess their possible impact on its business. Inventory Inventories are stated at the lower of cost or market with cost based on the first‑in, first‑out (FIFO) method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when selected for use in a clinical manufacturing campaign. Capitalization of Inventory Costs The company capitalizes inventory costs associated with its products prior to regulatory approval, when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. In determining whether or not to capitalize such costs, the company evaluates, among other factors, information regarding the drug candidate’s safety and efficacy, the status of regulatory submissions and communications with regulatory authorities and the outlook for commercial sales, including the existence of current or anticipated competitive drugs and the availability of reimbursement. In addition, the company evaluates risks associated with manufacturing the drug candidate and the remaining shelf‑life of the inventories. Obsolescence and Unmarketable Inventory The company periodically reviews its inventories for excess or obsolescence and write‑down obsolete or otherwise unmarketable inventory to its estimated net realizable value. Property, Plant and Equipment Property, plant and equipment are carried at cost, subject to review for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. The cost of normal, recurring, or periodic repairs and maintenance activities related to property, plant and equipment are expensed as incurred. The cost for planned major maintenance activities, including the related acquisition or construction of assets, is capitalized if the repair will result in future economic benefits. Prior to the separation, Property, plant and equipment comprised of assets whereby a majority of its use was dedicated to the hemophilia business. The company generally depreciates or amortizes the cost of its property, plant and equipment using the straight‑line method over the estimated useful lives of the respective assets, which are summarized as follows: Asset Category Useful Lives Land Not depreciated Buildings 15 to 40 years Leasehold Improvements Lesser of the useful life or the term of the respective lease Furniture and Fixtures 5 to 7 years Machinery and Equipment 5 to 20 years Computer Software and Hardware 3 to 5 years Acquired Intangibles Acquired intangibles include product rights, patents and in-process research and development (IPR&D) acquired in a business combination. IPR&D represents the fair value of research and development assets that have not reached technological feasibility. The value assigned to acquired IPR&D is determined by estimating the costs to develop the acquired technology into a commercial product, estimating revenue and costs associated with the product, adjusting the net cash flows for probability of success and discounting to present value. The estimated net cash flows consider the relevant market sizes and growth factors, expected trends in technology and the nature and expected timing of new product introductions by us and our competitors. The rates utilized to discount the net cash flows to their present value are commensurate with the stage of development of the projects and uncertainties in the economic estimates used in the projections. In estimating the probability of success, we utilize data regarding similar assets events from several sources, including industry studies and our own experience. Upon the acquisition of intangible assets, we complete an assessment of whether our acquisition constitutes the purchase of a single asset or a group of assets. We consider multiple factors in this assessment, including the nature of the technology acquired, the presence or absence of separate cash flows, the development process and stage of completion, quantitative significance and our rationale for entering into the transaction. If we acquire a business as defined under applicable accounting standards, then the acquired IPR&D is capitalized as an intangible asset. If we acquire an asset or group of assets that do not meet the definition of a business, then the acquired IPR&D is expensed on its acquisition date if it has no future alternative use. Future costs to develop these assets are recorded to research and development as they are incurred. We perform a qualitative assessment to determine whether any indicators for impairment exist. As a result of the assessment, the company concluded the carrying value of our acquired IPR&D exceeds its fair value. Acquired product rights and patents are recorded at fair value, assigned an estimated useful life, and are amortized over their estimated useful lives of approximately twelve years. See Note 9, Intangible Assets . Amortization is included in cost of sales in the consolidated statements of income. Goodwill Goodwill represents the difference between the purchase price and the fair value of the identifiable tangible and intangible net assets when accounted for as a business combination using the purchase method of accounting. Goodwill is not amortized, but reviewed for impairment. Goodwill is reviewed annually and whenever events or changes in circumstances indicate that the carrying value of the goodwill might not be recoverable. We compare the fair value of our reporting unit to its carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of our reporting unit, then we would need to determine the implied fair value of our reporting unit’s goodwill. If the carrying value of our reporting unit’s goodwill exceeds its implied fair value, then we would record an impairment loss equal to the difference. As described above in Note 1, Nature of Business and Basis of Preparation , we operate in one operating segment which we consider our only reporting unit. Impairment of Long‑Lived Assets Long‑lived assets to be held and used, including property, plant and equipment and definite‑lived intangible assets, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets or asset group may not be recoverable. Determination of recoverability is based on an estimate of undiscounted future cash flows resulting from the use of the asset and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written‑down to their fair values. Long‑lived assets to be disposed of are carried at fair value less costs to sell. Contingent Consideration The consideration for our acquisition includes future payments that are contingent upon the occurrence of various events. We recorded a liability for such contingent payments at fair value on the acquisition date. We estimated the fair value of contingent consideration through valuation models that incorporate probability-adjusted assumptions related to the likelihood of achieving the milestones and making related payments. Our contingent consideration is remeasured each reporting period. Changes in the fair value of our contingent consideration are recognized in our condensed consolidated statements of income. Changes in the fair value of the contingent consideration can result from changes to one or multiple inputs, including changes to the discount rates, changes in the probability of certain clinical events, regulatory approval, and the amount or timing of development and sales based milestones. Discount rates in our valuation models represent a measure of the weighted average cost of capital of the target associated with settling the liability. The period over which we discount our contingent consideration is based on the current development stage of the product candidates and our specific development plan for that product candidate. In estimating the probability of success, we utilize data regarding similar milestone events from several sources, including industry studies and our own experience. These fair value measurements are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the acquisition date and for each subsequent period. Accordingly, changes in assumptions could have a material impact on the amount of contingent consideration expense we record in any given period. Non-designated Foreign Currency Contracts Currency forward contracts are used as a part of our strategy to manage exposure related to foreign currency denominated monetary assets and liabilities. These currency forward contracts are not designated as cash flow, fair value or net investment hedges. The currency forward contracts are marked-to-market with changes in fair value recorded to other income (expense) and are entered into for periods consistent with currency transaction exposures, generally less than one year. Translation of Foreign Currencies The functional currency for the company’s non‑U.S. subsidiaries is their local currency. For non‑U.S. subsidiaries that transact in a functional currency other than the U.S. dollar, assets and liabilities are translated at current rates of exchange at the balance sheet date. Income and expense items are translated at the average foreign exchange rates for the period. Adjustments resulting from the translation of the financial statements of non‑U.S. operations into U.S. dollars are excluded from the determination of net income and are recorded in accumulated other comprehensive income, a separate component of equity. Contingencies We are currently involved in various claims and legal proceedings. Loss contingency provisions are recorded if the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated or a range of loss can be determined. These accruals represent management’s best estimate of probable loss. Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. On a quarterly basis, we review the status of each significant matter and assess its potential financial exposure. Significant judgment is required in both the determination of probability and the determination as to whether an exposure is reasonably estimable. Because of uncertainties related to these matters, accruals are based only on the best information available at the time. As additional information becomes available, we reassess the potential liability related to pending claims and litigation and may change our estimates. These changes in the estimates of the potential liabilities could have a material impact on our consolidated results of operations and financial position. Revenue Recognition The company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the price to the customer is fixed or determinable; and collectability is reasonably assured. Product Revenues We sell mainly to specialty pharmacies, hemophilia treatment centers, public and private hospitals and independent specialty distributors. Any discounts offered to these customers are reflected as on‑invoice discounts. We also sell to specialty distributors who receive both on‑invoice discounts as well as chargebacks for sales to various U.S. government agencies such as U.S. Public Health Service (PHS). Provisions for rebates, chargebacks to distributors, and discounts are provided for at the time the related sales are recorded, and are reflected as a reduction of sales. Reserves established for these discounts and allowances are classified as reductions of accounts receivable (if the amount is payable to our customer) or a liability (if the amount is payable to a party other than our customer). Our estimates take into consideration our historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Actual amounts may ultimately differ from our estimates. If actual results vary, we adjust these estimates, which could have an effect on earnings in the period of adjustment. To date historical adjustments have not been material. Product revenue reserves are categorized as follows: discounts and contractual adjustments. Discounts include trade term discounts and volume discounts. Trade term discounts relate to estimated obligations for credits to be granted to customers for remitting payment on their purchases within established incentive periods. Volume discounts are earned as customers reach certain tier levels based upon their purchases. Contractual adjustments primarily relate to Medicaid and PHS discounts. Product returns are insignificant and mainly resulting from product damaged in transit or incorrectly shipped. Collaborations Our development and commercialization arrangement with Sobi represents a collaborative arrangement because both Sobi and us are active participants and exposed to significant risks and rewards of the arrangement. Where we are the principal on sales transactions with third parties, we recognize revenue, cost of sales, including royalty cost of sales, and operating expenses on a gross basis in our income statement. We recognize payments between Sobi and us based upon their nature. These payments consist of royalty cost of sales, royalty revenue and contract manufacturing revenue. Royalty revenue and contract manufacturing revenue represent collaboration revenue in our income statement. See Note 4, Collaborations . Research and Development Expenses Research and development costs are expensed as incurred. Milestone payments prior to regulatory approval are expensed when the milestone is achieved. Payments made to counterparties on or after regulatory approval are capitalized and amortized over the remaining useful life of the related product. Amounts capitalized for such payments are included in acquired intangible assets, net of accumulated amortization. Also included in research and development expenses are allocations from Biogen. See Note 14, Related Parties. Income Taxes Deferred taxes are recognized for the future tax effects of temporary differences between financial and income tax reporting based on enacted tax laws and rates. With respect to uncertain tax positions, the company determines whether the position is more likely than not to be sustained upon examination, based on the technical merits of the position. Any tax position that meets the more‑likely‑than‑not recognition threshold is measured and recognized in the consolidated financial statements at the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement. The liability relating to uncertain tax positions is classified as current in the consolidated balance sheets to the extent the company anticipates making a payment within one year. Interest and penalties associated with income taxes are classified in the income tax expense line in the consolidated statements of income. Prior to the separation, the company’s income tax expense and deferred tax balances were calculated on a separate tax return basis although the company’s operations had historically been included in the tax returns filed by the respective Biogen entities, of which the company’s business was a part. For periods subsequent to the separation, Bioverativ files tax returns on its own behalf and its income tax expense and deferred income tax balances are recorded in accordance with the company’s standalone income tax positions. Biogen and Bioverativ entered into a tax matters agreement effective as of the date of separation. Accounting for Share‑Based Compensation In connection with the separation, we adopted our own share‑based compensation plans. Outstanding Biogen CSPUs, MSUs and PUs were converted to Bioverativ RSUs and outstanding Biogen stock options were converted to Bioverativ stock options. See Note 13, Share‑Based Compensation . We charge the estimated fair value of awards against income over the requisite service period, which is generally the vesting period. Where awards are made with non‑substantive vesting periods (for instance, where a portion of the award vests upon retirement eligibility), we estimate and recognize expense based on the period from the grant date to the date on which the employee is retirement eligible. We recognize forfeitures as they occur. The fair values of our stock option grants are estimated as of the date of grant using a Black‑Scholes option valuation model. The estimated fair values of the stock options are then expensed over the options’ vesting periods. The fair values of RSUs are based on the market value of our stock on the date of grant. Compensation expense for RSUs is recognized on a straight‑line basis over the applicable service period. New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies that we adopt as of the specified effective date. The following new standards issued by FASB were adopted by the company on January 1, 2017: · Accounting Standards Update (ASU) No. 2015‑11, Inventory (Topic 330): Simplifying the Measurement of Inventory. The new standard applies only to inventory for which cost is determined by methods other than last-in, first-out and the retail inventory method, which includes inventory that is measured using first in, first out (FIFO) or average cost. Inventory within the scope of this standard is required to be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The adoption of this standard did not have a material impact on our financial position, results of operations or statements of cash flows upon adoption. · ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. The new standard requires that deferred tax assets and liabilities be classified as noncurrent in a classified statement of financial position. The adoption of this standard did not have a material impact on our financial position, results of operations or statements of cash flows upon adoption. · ASU No. 2016‑09, Compensation‑Stock Compensation (Topic 718): Improvements to Employee Share‑Based Payment Accounting. The new standard requires recognition of the income tax effects of vested or settled awards in the income statement and involves several other aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The adoption of this standard did not have a material impact on our financial position, results of operations or statements of cash flows upon adoption. In the fourth quarter of 2017 we adopted the following standard: · In January 2017 the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment. This new standard simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The adoption of this standard did not have a material impact on our financial position or results of operations. The following new standards have been issued by FASB but are not yet effective as of December 31, 2017: · In May 2014 the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The FASB has subsequently issued amendments to ASU No. 2014-09 that have the same effective date and transition date of January 1, 2018. We expect to adopt these standards using the full retrospective method. We will apply all of the requirements of the new standards to each comparative period presented in accordance with the requirements on accounting changes. We are finalizing our assessment of the effect of adoption. Based on this assessment, we expect changes in our revenue recognition policy relating to the opt-in consideration payable by Sobi to us under our collaboration agreement with Sobi (See Note 4, Collaborations ). Currently the payment by Sobi of the opt-in consideration is recognized over the term of the commercialization period using a cross-royalty payment structure. Upon adoption of these standards, for the year ended December 31, 2016, the net present value of the remaining opt-in consideration will be recognized as revenue and note receivable. Commencing in 2017, royalty revenue will be recognized at the contractual 12% rate rather than the effective rate of 13-15%. Royalty cost of sales will be recognized at the contractual rate of 12% in North America and 17% outside North America instead of the effective rate of 10-11% and 15-16%, respectively. Upon adoption in Q1 2018, our balance sheet at December 31, 2017 is expected to increase by approximately $190 million due to the note receivable from Sobi. · In January 2016 the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new standard amends certain aspects of accounting and disclosure requirements of financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in a company's results of operations. The new standard will be effective for us on January 1, 2018. The adoption of this standard is not expected to have a material impact on our financial position or results of operations. · In February 2016 the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires that all lessees recognize the assets and liabilities that arise from leases on their balance sheet and disclose qualitative and quantitative information about their leasing arrangements. The new standard will be effective for us on January 1, 2019. The adoption of this standard is not expected to have a material impact on our results of operations but may impact our financial position. · In October 2016 the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfer of Assets Other Than Inventory. This new standard eliminates the deferral of the tax effects of intra-entity transfers of an asset other than inventory. Under the new standard, entities should recognize the income tax consequences on an intra-entity transfer of an asset other than inventory when the transfer occurs. This new standard will be effective for us on January 1, 2018 and will be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of this standard is not expected to have a material impact on our financial position. · In November 2016 the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The amendments in this update require that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This new standard will be effective for us on January 1, 2018. The adoption of this standard is not expected to have a material impact on our financial position. · In January 2017 the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This new standard clarifies the definition of a business and provides a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set of assets and activities is not a business. This new standard will be effective for us on January 1, 2018, however early adoption is permitted. The adoption of this standard is not expected to have a material impact on our financial position. · In May 2017 the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting. This new standard provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. This new standard will be effective for us on January 1, 2018. The adoption of this standard is not expected to have a material impact on our financial position or results of operations.

Acquisition of True North Thera

Acquisition of True North Therapeutics, Inc.	12 Months Ended
	Dec. 31, 2017
Acquisition of True North Therapeutics, Inc.
Acquisition of True North Therapeutics, Inc.	3. Acquisition of True North Therapeutics, Inc. On June 28, 2017, Bioverativ acquired all of the outstanding equity of True North Therapeutics, Inc. (True North), a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of first-in-class product candidates for complement-mediated diseases. At closing, we paid True North equityholders as of the acquisition date (True North equityholders) upfront consideration of $395.7 million plus assumed cash. True North equityholders are also eligible to receive additional payments of up to $425.0 million contingent on the achievement of future development, regulatory and sales milestones. The upfront consideration was paid with cash. The acquisition of True North was accounted for as a business combination using the acquisition method of accounting. The assets acquired and the liabilities assumed from True North have been recorded at their preliminary fair value as of June 28, 2017, the date of acquisition. The company’s audited consolidated financial statements included the results of True North from the date of acquisition. The company completed its evaluation of information, assumptions and valuation methodologies it used in its fair value of the purchase price consideration. The fair value of the purchase price consideration consisted of the following: (In millions) Estimated Fair Value Cash paid, net of cash acquired $ 395.7 Contingent consideration 188.5 Total purchase price consideration $ 584.2 The company’s allocation of the purchase price to the assets acquired and liabilities assumed as of December 31, 2017 are outlined below. As of December 31, (In millions) 2017 Current assets $ 0.6 Property, plant and equipment, net 0.6 In-process research and development (IPR&D) 590.0 Goodwill 170.7 Accounts payable and accrued expenses (4.0) Deferred tax liabilities (173.7) Final fair value of identifiable assets acquired and liabilities assumed $ 584.2 Intangible Assets IPR&D intangible assets totaling $590.0 million represent the value assigned to research and development (R&D) projects acquired from True North. These IPR&D intangible assets are capitalized and accounted for as indefinite-lived intangible assets and will be subject to impairment testing until completion or abandonment of the projects. Upon successful completion of each project, the company will make a separate determination of the estimated useful life of the IPR&D intangible assets and the related amortization will be recorded as an expense over the estimated useful life. Some of the more significant assumptions inherent in the development of those asset valuations include the estimated net cash flows for each year for each asset (including net revenues, cost of sales, R&D costs, selling and marketing costs, working capital/asset contributory asset charges and other cash flow assumptions), probability of success, the appropriate discount rate to select in order to measure the risk inherent in each future cash flow stream, the assessment of each asset’s life cycle, the potential regulatory and commercial success risks, competitive trends impacting the asset and each cash flow stream as well as other factors. The discount rate used to arrive at the present value at the acquisition date of the IPR&D intangible assets was 18.0% to reflect the internal rate of return and uncertainty in the cash flow projections. No assurances can be given that the underlying assumptions used to prepare the discounted cash flow analysis will not change. For these and other reasons, actual results may vary significantly from estimated results. Goodwill Goodwill, of $170.7 million as of December 31, 2017, which is not deductible for tax purposes, includes the value of net deferred tax liabilities associated with IPR&D. The table below presents a rollforward of goodwill: (In millions) Balance at December 31, 2016 $ — Additions 170.7 Balance at December 31, 2017 $ 170.7 Deferred tax liabilities Deferred tax liabilities includes the impact of IPR&D intangible assets which have no tax basis, partially offset by deferred tax assets associated with acquired net operating losses and research and development credits. Contingent Consideration True North equityholders are also eligible to receive additional payments of up to $425.0 million contingent on the achievement of future development, regulatory and sales milestones. The company estimated the fair value of the contingent consideration to be $188.5 million using a probability adjusted approach that considered the possible outcomes based on assumptions related to the timing and probability of the product launch, discount rates matched to the timing of first payment, and probability of success rates and discount adjustments on the related cash flows. Changes to assumptions used in the estimated fair value of contingent consideration were refinements based on current information as of December 31, 2017. The impact of these refinements was an increase of $9.9 million in the fair value of contingent consideration, which has been recorded as an increase in the contingent consideration liability and a research and development expense. Due to True North Equityholders In connection with the acquisition, we assumed $40.0 million of True North cash which is being held in escrow to satisfy specified indemnification obligations that arise within 18 months post closing. Any amounts remaining in escrow are payable to True North equityholders. The amounts in escrow are classified as short term restricted cash and amounts due to True North equityholders are classified as a short term liability as of December 31, 2017. Integration and Acquisition Costs During the year ended December 31, 2017, the company expensed $9.0 million relating to the acquisition and integration of True North, which has been recorded within selling, general and administrative in the company’s consolidated statements of income. Supplemental Disclosure of Pro Forma Information The following unaudited pro forma financial information presents the combined results of the operations of Bioverativ and True North as if the acquisition of True North had occurred as of January 1, 2016. The unaudited pro forma financial information is not necessarily indicative of what the consolidated results of operations actually would have been had the acquisitions been completed on January 1, 2016. In addition, the unaudited pro forma financial information does not purport to project the future results of operations of the company. For the Years Ended December 31, (In millions, except per share amounts) 2017 2016 Revenues $ 1,168.6 $ 887.4 Net income 341.0 407.7 Per share amounts: Net income per share - basic 3.15 3.78 Net income per share - diluted 3.14 3.78 The unaudited pro forma financial information above reflects a pro forma adjustment for the year ended December 31, 2017 of $11.6 million, related to integration and acquisition costs, net of tax incurred by Bioverativ and True North, including costs incurred by True North associated with its preparation for an initial public offering.

Collaborations

Collaborations	12 Months Ended
	Dec. 31, 2017
Collaborations
Collaborations	4. Collaborations In connection with the company’s business strategy, the company has entered into various collaboration agreements which provide the company with rights to develop, produce and market products using certain know‑how, technology and patent rights maintained by the company’s collaborative partners. Terms of the various collaboration agreements may require the company to make milestone payments upon the achievement of certain product research and development objectives and pay royalties on future sales, if any, of commercial products resulting from the collaboration. Swedish Orphan Biovitrum AB (publ) In January 2007, Biogen acquired 100% of the stock of Syntonix Pharmaceuticals (Syntonix). Syntonix, now known as Bioverativ Therapeutics Inc. (formerly Biogen Hemophilia Inc.), had previously entered into a development and commercialization agreement with Sobi to jointly develop and commercialize Factor VIII and Factor IX hemophilia products, including ELOCTATE and ALPROLIX. Under the development and commercialization agreement, as has been amended and restated, Bioverativ has commercial rights for North America (the Bioverativ North America Territory) and for all other markets outside of the Sobi territory (the Bioverativ Direct Territory), which consists of Europe, Russia and certain countries in Northern Africa and the Middle East (the Sobi Territory). Under the development and commercialization agreement, prior to May 5, 2024, either Bioverativ or Sobi may present a compound construct as a potential product candidate that the parties may consider developing and commercializing under the collaboration. Upon Sobi's election to treat a compound construct as a product, and in the case of a novel compound construct upon Sobi's payment of an upfront fee, Sobi is granted the right to opt-in to such compound construct and become responsible for final development and commercialization of that compound construct in Sobi's commercialization territory. Generally, upon opt-in, Sobi becomes obligated to make an advance payment and reimburse Bioverativ for certain development expenses incurred with respect to the compound construct. Until Sobi's portion of the development expenses are fully paid, Sobi's royalty rate payable to Bioverativ is increased, and the royalty payment payable by Bioverativ to Sobi for the sale of products in Bioverativ's territory is decreased. In November 2014, Sobi exercised its option under the agreement to assume final development and commercialization activities in the Sobi Territory for ELOCTA (the trade name for ELOCTATE in the European Union). In July 2015, Sobi exercised its option under the agreement to assume final development and commercialization of ALPROLIX within the Sobi Territory. Upon each exercise of opt‑in right under the terms of the development and commercialization agreement, Sobi made a $10.0 million payment. Upon European Medicines Agency (EMA) regulatory approval of each of ELOCTA and ALPROLIX, Sobi was obligated to reimburse Bioverativ 50% of all shared manufacturing and development expenses incurred by Bioverativ from October 1, 2009 through the earlier of the date on which Sobi is registered as the marketing authorization holder for the applicable product or 90 days post‑regulatory approval, as well as 100% of certain development expenses incurred exclusively for the benefit of the Sobi Territory (the Opt‑In Consideration). ELOCTA was approved by the European Commission (EC) in November 2015. The Opt‑In Consideration and aggregate amount reimbursable by Sobi for ELOCTA was $211.0 million. As of December 31, 2017, approximately $90.5 million remained reimbursable by Sobi. ALPROLIX was approved by the EC in May 2016. The Opt‑In Consideration and aggregate amount reimbursable by Sobi for ALPROLIX was $184.7 million. As of December 31, 2017, approximately $97.4 million remained reimbursable by Sobi. The Opt‑In Consideration for each product is being paid by Sobi using a cross‑royalty cash payment structure for sales in each company’s respective territories. If the reimbursement of the Opt‑in Consideration for a product has not been achieved within six years of the first commercial sale of such product (the Reimbursement Period), the company maintains the right to require Sobi to pay any remaining balances due to us within 90 days of the six-year anniversary date of the first commercial sale. After Sobi’s Opt‑In Consideration has been repaid, the royalty paid and received by the company resets to the contractual royalty rate of 12%. Upon Sobi’s first commercial sale in 2016, and during the Reimbursement Period, the royalty rate the company will pay Sobi on sales of ELOCTATE and ALPROLIX in the Bioverativ North American Territory is 7% and Bioverativ Direct Territory is 12%. After the Reimbursement Period concludes, the royalty rate we pay to Sobi increases by 5%. For the year ended December 31, 2017, we are recording cost of sales at the effective royalty rate of approximately 11%. For the year ended December 31, 2016, the effective royalty rate was approximately 10%. The company is accounting for the development and commercialization agreement under a right to use model and is recognizing revenue over the commercialization period. The royalty rate received by the company, during the Reimbursement Period on sales of ELOCTATE and ALPROLIX in Sobi’s territory is 17%. After the Reimbursement Period concludes, the royalty we receive decreases to 12%. We are recording revenue at an effective royalty rate of approximately 14%. In September 2014, Sobi elected to treat BIVV001 (rFVIIIFc‑VWF‑XTEN), a compound construct developed using the XTEN technology, as subject to the collaboration. In February 2017, Sobi elected to treat BIVV002 (rFIXFc-XTEN), a preclinical compound construct developed using the XTEN technology, as subject to the collaboration. In consideration for its election, Sobi paid $6.2 million, which has been included as a component of research and development expense. If Sobi exercises its opt-in right for BIVV001 or BIVV002, as the case may be, it will become responsible for final development and commercialization of the applicable product in the Sobi Territory. Further, in general upon opt-in, Sobi will be obligated to reimburse Bioverativ 50% of all shared manufacturing and development expenses incurred by Bioverativ from the period of opt-in through the earlier of the date on which Sobi is registered as the marketing authorization holder for the applicable product or 90 days post‑regulatory approval, as well as 100% of certain development expenses incurred exclusively for the benefit of the Sobi Territory. Sangamo Therapeutics, Inc. In January, 2014, Biogen MA Inc., a subsidiary of Biogen, entered into an exclusive worldwide research, development and commercialization collaboration and license agreement with Sangamo under which both companies agreed to develop and commercialize product candidates for the treatment of two inherited blood disorders, sickle cell disease and beta-thalassemia. In connection with the separation, we succeeded to Biogen's rights and obligations under this agreement. Under the collaboration, Sangamo is responsible for identifying a product candidate for the treatment of beta-thalassemia and advancing that candidate through a completed Phase 1 human clinical trial, at which point we would assume responsibility for development. The collaboration contemplates our joint development of a sickle cell disease candidate through the potential filing of an investigational new drug application, after which we would assume clinical responsibilities. We have the right to lead the global development and commercialization efforts and Sangamo has the option to assume co-promotion responsibilities in the United States. The collaboration is currently in the pre-clinical stage of development. Under the terms of the agreement, Sangamo is eligible to receive up to $215.0 million related to development, regulatory and commercialization milestones as well as tiered low to mid double-digit royalties related to product sales. Bicycle Therapeutics Research Collaboration In August 2017, we entered into a research collaboration agreement with Bicycle Therapeutics (Bicycle), a biotechnology company that is pioneering a new class of medicines based on its novel bicyclic peptide (Bicycle®) product platform. The collaboration will focus on the discovery, development and commercialization of therapies for hemophilia and sickle cell disease. Under this agreement, Bicycle will be responsible for leading initial discovery activities through lead optimization to candidate selection for three programs. Bioverativ will lead preclinical and clinical development, as well as subsequent marketing and commercialization efforts. Under the agreement, we paid Bicycle a $10.0 million upfront payment. Bicycle is eligible to receive up to $410.0 million related to development, regulatory and commercialization milestones as well as tiered single to low double-digit royalties related to product sales. Bioverativ will also reimburse Bicycle for internal and external program-related costs.

Debt and Credit Agreements

Debt and Credit Agreements	12 Months Ended
	Dec. 31, 2017
Debt and Credit Agreements
Debt and Credit Agreements	5. Debt and Credit Agreements On June 28, 2017, we entered into a $175.0 million revolving credit facility (Credit Facility), by and among the company and certain subsidiaries as borrowers, and Bank of America, N.A. and other lenders party thereto (the Lenders). The Credit Facility matures on June 28, 2020. Borrowings under the Credit Facility bear interest, at our option, at either a base rate or a Eurocurrency rate, in each case plus an applicable margin. Under the Credit Facility, the applicable margin on base rate loans ranges from 0.50% to 1.00% and the applicable margin on Eurocurrency loans ranges from 1.50% to 2.00%, in each case, based on our consolidated leverage ratio (the ratio of our total consolidated funded indebtedness to our consolidated EBITDA for the most recently completed four fiscal quarter period). Borrowings under the Credit Facility are guaranteed by certain of our domestic subsidiaries. The Credit Facility contains customary representations and warranties and affirmative and negative covenants, including financial covenants to maintain (x) a maximum consolidated leverage ratio of 3.00 to 1.00 (which ratio may, at the election of the Company, be increased to 4.00 to 1.00 upon consummation of a material acquisition, and which shall step down by 0.25x after each full fiscal quarter following such acquisition and return to 3.00 to 1.00 after four full fiscal quarters) and (y) a minimum consolidated interest coverage ratio (the ratio of our EBITDA to consolidated interest charges) of 3.00 to 1.00. As of December 31, 2017, the company was in compliance with the financial covenants under the Credit Facility. As of December 31, 2017, there were no amounts outstanding under the Credit Facility.

Financial instruments and fair

Financial instruments and fair value measurements	12 Months Ended
	Dec. 31, 2017
Financial instruments and fair value measurements
Financial instruments and fair value measurements	6. Financial instruments and fair value measurements We have certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. · Level 1 – Fair values are determined by utilizing quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access; · Level 2 – Fair values are determined by utilizing quoted prices for similar assets and liabilities in active markets or other market observable inputs such as interest rates, yield curves and foreign currency spot rates; and · Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The majority of our financial assets have been classified as Level 2. Our financial assets (which include our cash equivalents, plan assets for deferred compensation and derivative contracts) have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing market observable data. These observable market inputs include reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates and other industry and economic events. For contingent consideration obligations, the fair value measurements are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the applicable acquisition date and for each subsequent period. Accordingly, changes in assumptions could have a material impact on the amount of contingent consideration expense we record in any given period. The table below presents information about our assets that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques we utilized to determine such fair value: As of December 31, 2017 (In millions) Total Quoted Prices Significant Other Significant Assets Cash equivalents $ 411.1 $ — $ 411.1 $ — Plan assets for deferred compensation 18.7 — 18.7 — Derivative contracts 1.1 — 1.1 — Total $ 430.9 $ — $ 430.9 $ — Liabilities Derivative contracts 0.7 — 0.7 — Contingent consideration obligations $ 198.4 $ — $ — $ 198.4 Total $ 199.1 $ — $ 0.7 $ 198.4 As of December 31, 2017, cash equivalents were comprised of money market funds with maturities less than 90 days from the date of purchase. As of December 31, 2017, the notional amount of outstanding undesignated foreign currency derivative instruments was $123.1 million. The fair value of derivative contracts assets of $1.1 million was a component of other current assets and the fair value of derivative contracts liabilities of $0.7 million was a component of other current liabilities. For the year ended December 31, 2017, foreign currency derivative gain was $2.2 million, and was a component of other income (expense). There were no hedge gains or losses in any other period presented. There have been no material impairments of our assets measured and carried at fair value during the year ended December 31, 2017. In addition, there were no changes in valuation techniques or inputs utilized or transfers between fair value measurement levels during the year ended December 31, 2017. The table below presents a rollforward of contingent consideration obligations: (In millions) Balance at December 31, 2016 $ — Additions 188.5 Research and development expenses recognized due to change in fair value 9.9 Balance at December 31, 2017 $ 198.4 As of December 31, 2016, we had no financial assets and liabilities that were recorded at fair value.

Reserves for Discounts and Allo

Reserves for Discounts and Allowances	12 Months Ended
	Dec. 31, 2017
Reserves for Discounts and Allowances
Reserves for Discounts and Allowances	7. Reserves for Discounts and Allowances Following the company’s product launches, the company began recognizing reserves for discounts and allowances related to products revenue. An analysis of the change in reserves is summarized as follows: Contractual (In millions) Discounts Adjustments Returns Total Balance at December 31, 2015 $ 5.8 $ 16.0 — $ 21.8 Provision related to current period sales 160.9 165.2 1.3 327.4 Adjustment related to prior period sales (2.0) (0.7) — (2.7) Credits/payments made (158.7) (154.0) (1.0) (313.7) Balance at December 31, 2016 $ 6.0 $ 26.5 0.3 $ 32.8 Provision related to current period sales 178.0 304.1 0.7 482.8 Adjustment related to prior period sales (1.3) 3.2 0.3 2.2 Credits/payments made (176.9) (282.2) (0.3) (459.4) Balance at December 31, 2017 $ 5.8 $ 51.6 $ 1.0 $ 58.4 As of December 31, (In millions) 2017 2016 Reduction of accounts receivable $ 10.5 $ 11.1 Current liability 47.9 21.7 Total reserves $ 58.4 $ 32.8

Inventory

Inventory	12 Months Ended
	Dec. 31, 2017
Inventory
Inventory	8. Inventory The components of inventory are summarized as follows: As of December 31, (In millions) 2017 2016 Raw materials $ 0.4 $ 42.9 Work in process 11.4 227.2 Finished goods 28.8 31.9 Total inventory $ 40.6 $ 302.0 Inventory and inventoriable costs written down as a result of excess, obsolescence, unmarketability or other reasons are charged to cost of sales. There were $8.8 million, $13.5 million and $1.3 million of write-offs in the years ended December 31, 2017, 2016 and 2015, respectively. Inventory consists of amounts contributed as part of the separation. Since the separation, we have drawn down contributed inventory. In connection with the separation, certain raw material and work in process inventory totaling $179.0 million was retained by Biogen. This inventory is subject to the terms and conditions of our manufacturing and supply agreement with Biogen. In the fourth quarter of 2017, we commenced purchasing inventory from Biogen pursuant to a manufacturing and supply agreement.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
Intangible Assets
Intangible Assets	9. Intangible Assets Our intangible assets consist of developed technology milestones and IPR&D. Developed technology primarily relates to approval milestones for ALPROLIX paid to the former Syntonix shareholders in 2014 and 2016. IPR&D consists of assets acquired as a result of our acquisition of True North and primarily relates to BIVV009 (formerly TNT009), a first-in-class monoclonal antibody in development for the treatment of cold agglutinin disease (CAgD). Intangible assets, net of accumulated amortization are summarized as follows: As of As of December 31, 2017 December 31, 2016 Estimated Accumulated Accumulated (In millions except for estimated life) Life Cost Amortization Net Cost Amortization Net Developed technology 11 years $ 61.7 $ (15.8) $ 45.9 $ 61.7 $ (10.0) $ 51.7 IPR&D Indefinite 590.0 — 590.0 — — — Total $ 651.7 $ (15.8) $ 635.9 $ 61.7 $ (10.0) $ 51.7 During the years ended December 31, 2017, 2016 and 2015, amortization expense associated with developed technology assets was $5.8 million, $4.8 million, and $3.0 million, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment
Property, Plant and Equipment	10. Property, Plant and Equipment Property, plant and equipment are recorded at historical cost, net of accumulated depreciation. Components of property, plant and equipment, net are summarized as follows: As of December 31, (In millions) 2017 2016 Buildings $ — $ 8.0 Leasehold improvements 8.7 — Machinery and equipment 30.8 21.0 Computer software and hardware 6.6 5.9 Furniture and fixtures 0.9 0.5 Construction in progress 1.4 6.9 Total cost 48.4 42.3 Less: accumulated depreciation 24.4 13.9 Total property, plant and equipment, net $ 24.0 $ 28.4 In connection with the separation, certain property, plant and equipment, mainly buildings and associated accumulated depreciation totaling $9.8 million was retained by Biogen. During the years ended December 31, 2017, 2016 and 2015, depreciation expense associated with property, plant and equipment was $8.7 million, $48.6 million, and $12.6 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes
Income Taxes	11. Income Taxes The company’s effective tax rate was 21.3% during the year ended December 31, 2017 as compared to (50.6)% in the prior year comparative period. The company’s effective income tax rate for year ended December 31, 2017 differs from the U.S. federal statutory rate mainly due to state and local taxes partially offset by credits, permanent items, and the impact of a one-time deferred tax revaluation under the 2017 Tax Act. The company’s effective income tax rate for year ended December 31, 2016 differ from the U.S. federal statutory rates mainly due to the release of a previously established valuation allowance. Prior to the separation, the company’s income tax expense and deferred tax balances were calculated on a separate tax return basis although the company’s operations had historically been included in the tax returns filed by the respective Biogen entities, of which the company’s business was a part. For periods subsequent to the separation, Bioverativ files tax returns on its own behalf and its income tax expense and deferred income tax balances are recorded in accordance with the company’s standalone income tax positions. Biogen and Bioverativ entered into a tax matters agreement effective as of the date of separation. Under the terms of the tax matters agreement Bioverativ may be required to indemnify Biogen for certain tax matters. To date, no amounts have been identified. The 2017 Tax Act, which was signed into law on December 22, 2017, has resulted in significant changes to the U.S. corporate income tax system. These changes include a federal statutory rate reduction from 35% to 21%, the elimination or reduction of certain domestic deductions and credits and limitations on the deductibility of interest expense and executive compensation. The 2017 Tax Act also transitions international taxation from a worldwide system to a modified territorial system and includes base erosion prevention measures on non-U.S. earnings. These changes are effective beginning in 2018. The 2017 Tax Act also includes a one-time mandatory deemed repatriation tax on accumulated foreign subsidiaries' previously untaxed foreign earnings (the Transition Toll Tax). Changes in tax rates and tax laws are accounted for in the period of enactment. During the year ended December 31, 2017, we recorded a benefit totaling $58.8 million related to our current estimate of the provisions of the 2017 Tax Act. The preliminary estimate of Transition Toll Tax was immaterial. Our preliminary estimate of the Transition Toll Tax and the remeasurement of our deferred tax assets and liabilities is subject to the finalization of management's analysis related to certain matters, such as developing interpretations of the provisions of the 2017 Tax Act, changes to certain estimates and amounts related to the earnings and profits of certain subsidiaries and the filing of our tax returns. U.S. Treasury regulations, administrative interpretations or court decisions interpreting the 2017 Tax Act may require further adjustments and changes in our estimates, which could have a material adverse effect on our business, results of operations or financial conditions. The final determination of the Transition Toll Tax and the remeasurement of our deferred tax assets and liabilities will be completed as additional information becomes available, but no later than one year from the enactment of the 2017 Tax Act. Income before Income Tax Provision and Income Tax Expense For the Years Ended December 31, (In millions) 2017 2016 2015 Income (loss) before income tax expense (benefit): Domestic $ 444.0 $ 284.1 $ 94.2 Foreign 7.9 7.8 4.4 Total $ 451.9 $ 291.9 $ 98.6 Income tax expense (benefit): Current Domestic $ 140.8 $ 8.4 $ — Foreign 3.1 2.4 1.4 Deferred Domestic (47.3) (158.5) (11.4) Foreign (0.3) — — Total income tax expense (benefit) $ 96.3 $ (147.7) $ (10.0) Deferred Tax Assets and Liabilities As of December 31, (In millions) 2017 2016 Deferred tax assets Net operating loss $ 21.6 $ 85.5 Tax credits 3.6 57.4 Inventory, other reserves, and accruals 12.8 14.5 Share-based compensation 6.7 3.4 Intangibles, net — 9.5 Deferred revenue 9.2 3.6 Other 1.2 — Valuation allowance — — Total deferred tax assets $ 55.1 $ 173.9 Deferred tax liabilities Purchased intangible assets $ (140.4) $ (16.3) Depreciation and amortization, net (2.7) (3.4) Total deferred tax liabilities $ (143.1) $ (19.7) In addition to deferred tax assets and liabilities, we have recorded prepaid tax and deferred charges related to intercompany transactions. As of December 31, 2017 the total deferred charges and prepaid taxes were $26.0 million. Income Tax Expense Reconciliation For the Years Ended December 31, 2017 2016 2015 Statutory rate 35.0 % 35.0 % 35.0 % State taxes 2.1 0.8 1.0 Taxes on foreign earnings — (0.1) (0.3) Tax rate change (13.0) — — Credits and NOLs (5.5) (0.7) (3.0) Changes in valuation allowance — (84.8) (42.7) Other permanent items 2.2 (1.3) (0.2) Other 0.5 0.5 — Effective income tax rate 21.3 % (50.6) % (10.2) % Our effective tax rate for 2017 compared to 2016 fluctuated primarily due to a $58.8 million one-time deferred tax revaluation based on recent tax law changes in 2017 and the release of the $247.3 million valuation allowance on our domestic deferred tax assets in 2016. Our effective tax rate for 2016 compared to 2015 benefitted primarily due to the release of a $247.3 million valuation allowance release in 2016. As of December 31, 2017, we had acquired net operating losses and general business credit carry forwards for federal income tax purposes of approximately $68.8 million and $4.0 million, respectively, which begin to expire in 2025 and 2020, respectively. Additionally, for state income tax purposes, we had acquired net operating loss carry forwards of approximately $102.3 million, which begin to expire in 2033. Internal Revenue Code Section 382 limits the use of net operating loss and tax credit carryforwards in the case of an “ownership change” of a corporation. Any ownership changes, as defined, may restrict utilization of carryforwards. In assessing the realizability of our deferred tax assets, we have considered whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. In making this determination, under the applicable financial reporting standards, we are allowed to consider the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies. Our estimates of future taxable income take into consideration, among other items, our estimates of future income tax deductions related to the exercise of stock options. Based upon the reversal of taxable temporary differences, its level of historical taxable income and income tax liability and projections for future taxable income over the periods in which the deferred tax assets are utilizable, we believe it is more likely than not that we will realize the net benefits of the deferred tax assets of our wholly owned subsidiaries. In the event that actual results differ from our estimates or we adjust our estimates in future periods, we may need to establish a valuation allowance, which could materially impact our financial position and results of operations. As of December 31, 2017, we are subject to taxation in the U.S. federal jurisdiction, various U.S. states, and foreign jurisdictions. The Company is subject to examination for tax years beginning in 2017.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2017
Earnings per Share
Earnings per Share	12. Earnings per Share The denominator for basic earnings per common share (EPS) is the weighted-average number of common shares outstanding during the period. The dilutive effect of outstanding stock options and time-vested restricted stock units is reflected in the denominator for diluted EPS using the treasury stock method. The numerator for both basic and diluted EPS is net income. On February 1, 2017, Biogen distributed approximately 108 million shares of Bioverativ common stock to its shareholders. The computation of basic and dilutive EPS for periods prior to the separation was calculated using the shares distributed. Basic and diluted earnings per share are calculated as follows: For the Years Ended December 31, (In millions) 2017 2016 2015 Numerator: Net income $ 355.6 $ 439.6 $ 108.6 Denominator: Weighted average number of common shares outstanding 108.1 108.0 108.0 Effect of dilutive securities: Stock options — — — Time-vested restricted stock units 0.4 — — Dilutive potential common shares 0.4 — — Shares used in calculating diluted earnings per share 108.5 108.0 108.0 The computation of diluted earnings per share excludes 2.2 million of outstanding common share equivalents for stock options for the year ended December 31, 2017, as compared to 2.5 million of outstanding common share equivalents for stock options and time-vested restricted stock units for the years ended December 31, 2016 and 2015 as the effect is anti-dilutive.

Share Based Compensation

Share Based Compensation	12 Months Ended
	Dec. 31, 2017
Share Based Compensation
Share Based Compensation	13. Share‑Based Compensation Bioverativ Share‑Based Compensation Plans In connection with the separation, we adopted our own share‑based compensation plans. Specifically, we adopted the Bioverativ Inc. 2017 Omnibus Equity Plan (the Omnibus Plan); the Bioverativ Inc. 2017 Non‑Employee Directors Equity Plan (the Directors Plan); and the Bioverativ Inc. 2017 Employee Stock Purchase Plan (ESPP). Cash-settled performance units (CSPUs), market stock units (MSUs), performance‑vested restricted stock units (PUs) and restricted stock units (RSUs) granted under Biogen 2008 Omnibus Equity Plan to Biogen employees who became employees of Bioverativ were converted into Bioverativ RSUs, and stock options held by Biogen employees who became employees of Bioverativ were converted into Bioverativ stock options, each according to the terms of an employee matters agreement entered into between Biogen and Bioverativ in connection with the separation (converted awards). Converted awards, as well as future awards issued to Bioverativ officers, directors and employees, will be awarded under, and subject to the terms of, the Omnibus Plan, the Directors Plan and the ESPP, as the case may be. Unless extended or earlier terminated, the term of the awards under these plans shall be 10 years from the effective date. The maximum number of shares of common stock subject to options granted to any participant, and that may be granted as RSUs, shall not exceed an aggregate of 2,250,000 in any calendar year. The maximum aggregate number of shares of common stock available for purchase under the ESPP by eligible employees will be 1,625,000 shares. The following table provides share-based compensation expense by statement of income line item for the years ended December 31, 2017, 2016 and 2015: For the Years Ended December 31, (In millions) 2017 2016 2015 Cost of sales $ — $ 7.3 $ 2.1 Research and development 5.0 3.7 4.8 Selling, general and administrative 27.0 4.3 6.3 Total share-based compensation expense $ 32.0 $ 15.3 $ 13.2 During the year ended December 31, 2017 and subsequent to the separation, Bioverativ awarded share-based compensation grants consisting of 2.3 million stock options and 0.4 million RSUs, with respect to the company’s employees. Post-Separation Stock Options Stock options awarded to employees generally vest one-third per year over three years on the anniversary of the date of grant, or upon the third anniversary of the date of the grant, provided the employee remains continuously employed with us, except as otherwise provided in the plan. Options granted are exercisable at a price per share not less than the fair market value of the underlying common stock on the date of grant. The estimated fair value of stock option, including the effect of forfeitures, is recognized over the options’ vesting periods. The fair value of the stock options granted in 2017 was estimated as of the date of grant using a Black-Scholes option valuation model. The weighted-average Black-Scholes assumptions used in estimating the fair value of stock options granted by Bioverativ following the separation during the year ended December 31, 2017, along with the weighted-average grant-date fair values, were as follows: For the Years Ended December 31, 2017 Expected volatility 40.0% Range of expected life (in years) 4 ̶ 5 Range of risk-free interest rate 1.72% ̶ 2.13% Dividend yield ̶ Range of fair value per stock option $16.78 ̶ $23.38 Expected volatility was determined using an average of peer companies’ expected volatility. As of December 31, 2017, the unrecognized compensation cost related to all unvested stock options held by Bioverativ’s employees of $19.8 million is expected to be recognized as expense over a weighted-average period of 2.2 years. As of December 31, 2017, no stock options were exercisable. The following table summarizes our stock option activity: Weighted Average Per Share Grant (In thousands, except per share amounts) Shares Date Fair Value Outstanding at December 31, 2016 — $ — Granted 2,254.5 16.98 Exercised — — Cancelled (91.2) 17.61 Outstanding at December 31, 2017 2,163.3 $ 16.97 In connection with the merger with Sanofi, the stock options outstanding as of December 31, 2017 will accelerate and become fully vested and will be canceled and converted into the right to receive the $105.0 per share less the applicable exercise price in cash. See Note 21, Subsequent Events to our audited consolidated financial statements included in this Form 10-K. Restricted Stock Units RSUs awarded to employees generally vest one-third per year over three years on the anniversary of the date of grant, or upon the third anniversary of the date of the grant. Shares of our common stock will be delivered to the employee upon vesting, subject to payment of applicable withholding taxes. The vesting of these awards is subject to the respective employee's continued employment. The fair value of all RSUs is based on the market value of our stock on the date of grant. Compensation expense, including the effect of forfeitures, is recognized over the applicable service period. As of December 31, 2017, the unrecognized compensation cost related to all unvested RSUs held by Bioverativ employees of $13.8 million is expected to be recognized as expense over a weighted-average period of 1.4 years. The following table summarizes our RSU activity: Weighted Average Per Share Grant (In thousands, except per share amounts) Shares Date Fair Value Unvested at December 31, 2016 348.6 $ 46.86 Granted 401.4 46.79 Conversions 337.4 44.98 Vested (227.5) 47.69 Forfeited (55.2) 46.30 Unvested at December 31, 2017 804.7 $ 45.84 Conversions relate to Biogen MSUs, Biogen CSPUs and Biogen PUs that were converted to RSUs upon separation. The components of conversions are as follows: (In thousands) Shares RSUs converted from MSUs 155.0 RSUs converted from CSPUs 43.6 RSUs converted from PUs 138.8 Total 337.4 In connection with the merger with Sanofi, the RSUs outstanding as of December 31, 2017 will accelerate and become fully vested and will be canceled and converted into the right to receive the $105.0 per share in cash. See Note 21, Subsequent Events to our audited consolidated financial statements included in this Form 10-K. Pre-separation Market Stock Units MSUs awarded by Biogen to Bioverativ employees vest in three equal annual increments beginning on the first anniversary of the grant date. The vesting of these awards is subject to the respective employee's continued employment. Compensation expense, including the effect of forfeitures, is recognized over the applicable service period. MSUs were valued using a lattice model with a Monte Carlo simulation. This valuation methodology utilized several key assumptions, the 30 calendar day average Biogen closing stock price on the date of grant, expected volatility of Biogen’s stock price, risk-free rates of return and expected dividend yield. The assumptions used in Biogen’s valuation are summarized as follows: For the Years Ended December 31, 2016 2015 Expected dividend yield ̶ ̶ Range of expected stock price volatility 38.2% - 40.7% 31.0% - 33.2% Range of risk-free interest rates 0.6% - 0.9% 0.2% - 1.0% 30 calendar day average stock price on grant date $260.67 - $304.86 $277.35 - $426.27 Weighted-average per share grant date fair value $326.65 $499.25 Cash-Settled Performance Units CSPUs awarded by Biogen to Bioverativ employees vest in three equal annual increments beginning on the first anniversary of the grant date. The vesting of these awards is subject to the respective employee's continued employment with such awards settled in cash. Compensation expense, including the effect of forfeitures, is recognized over the applicable service period. Performance-Vested Restricted Stock Units PUs awarded by Biogen to certain Bioverativ employees in the form of restricted stock units that may be settled in cash or shares of Biogen common stock at the sole discretion of the Compensation and Management Development Committee of Biogen's board of directors. These awards were structured and accounted for the same way as the cash settled performance units, and vest in three equal annual increments beginning on the first anniversary of the grant date. Compensation expense, including the effect of forfeitures, is recognized over the applicable service period. The vesting of these awards is subject to the respective employee's continued employment.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Parties
Related Parties	14. Related Parties Under the terms of the transition services agreement entered into with Biogen in connection with the separation, Biogen provides various services on an interim, transitional basis. The services provided by Biogen to Bioverativ consist of certain information technology, quality, regulatory, research and supply chain. These services are generally provided on a cost-plus basis. The services are generally expected to extend for up to 2 years following the separation. For the company’s operations in the United States and Canada transfer of marketing authorizations and other regulatory requirements did not occur by the separation date of February 1, 2017. As a result, the company entered into a commercial operations agreement with Biogen for the United States and Canada. Under the terms of the commercial operations agreements, until the Company has obtained the various required authorizations, Biogen agreed to perform certain services related to the distribution of finished goods to the company’s customers. The company is responsible for the business activities conducted by Biogen on its behalf, and is subject to the risks and entitled to the benefits generated by these operations and assets. As a result, the related liabilities and results of operations have been reported in the company’s consolidated financial statements as of and for the year ended December 31, 2017. Net sales related to these operations totaled $668.8 million during the year ended December 31, 2017. In May 2017, the Canadian marketing authorizations transferred to Bioverativ and in September 2017, the U.S. marketing authorizations transferred to Bioverativ. In July 2017 and October 2017, the commercial operations agreements in Canada and the United States, respectively, were completed. The company and Biogen also entered into a manufacturing and supply agreement whereby Biogen continues to produce ELOCTATE and ALPROLIX for us on a cost‑plus basis. As products were historically transferred at cost between Biogen and Bioverativ, these manufacturing and supply arrangements will result in changes to cost of goods sold in future periods. The company and Biogen also entered into a separation and distribution agreement, tax matters agreement, an employee matters agreement. As of December 31, 2017, total amount due to Biogen associated with transition service and manufacturing and supply agreements was $90.5 million. Corporate Overhead and Other Allocations from Biogen Prior to the separation, the company did not historically operate as a standalone business and had various relationships with Biogen whereby Biogen provided services to the company. These consolidated financial statements include an allocation from Biogen to us for certain research and development and selling, general and administrative costs not directly attributable to the hemophilia business of Biogen. For more information, see Note 1, Nature of Business and Basis of Preparation. For the years ended December 31, 2017, the allocations are for the period from January 1, 2017 through the separation date. These allocations were reflected as follows in the consolidated financial statements: For the Years Ended December 31, (In millions) 2017 2016 2015 Research and development allocations $ 6.5 $ 88.7 $ 84.5 Selling, general and administrative allocations 5.1 60.7 64.0 Other (income) expense, net allocations 0.2 0.6 0.1 Total corporate overhead and other allocations from Biogen $ 11.8 $ 150.0 $ 148.6

Other Consolidated Financial St

Other Consolidated Financial Statement Detail	12 Months Ended
	Dec. 31, 2017
Other Consolidated Financial Statement Detail
Other Consolidated Financial Statement Detail	15. Other Consolidated Financial Statement Detail Accrued Expenses and Other Current Liabilities Accrued expenses and other consists of the following: As of December 31, (In millions) 2017 2016 Revenue-related rebates $ 47.9 $ 21.7 Employee compensation and benefits 52.4 15.9 Research and development 9.9 5.5 Royalty and collaboration 38.8 26.6 Short-term portion of contingent consideration 49.2 — Taxes payable 9.4 10.8 Other 25.9 8.8 Total accrued expenses and other current liabilities $ 233.5 $ 89.3 Long‑Term Liabilities Long‑term liabilities consist of the following: As of December 31, (In millions) 2017 2016 Employee compensation and benefits $ — $ 18.7 Sobi payments 87.8 45.0 Other 4.7 — Total long term liabilities $ 92.5 $ 63.7

Litigation

Litigation	12 Months Ended
	Dec. 31, 2017
Litigation
Litigation	16. Litigation From time to time, we may be involved in various claims and legal proceedings. With respect to some loss contingencies, an estimate of the possible loss or range of loss cannot be made until management has further information, including, for example, (i) which claims, if any, will survive dispositive motion practice; (ii) information to be obtained through discovery; (iii) information as to the parties’ damages claims and supporting evidence; (iv) the parties’ legal theories; and (v) the parties’ settlement positions. Subject to the terms of the separation agreement we entered into with Biogen, the company may be responsible for certain liabilities relating to the following legal matters involving Biogen prior to the separation, solely to the extent such liabilities relate to, arise out of or result from hemophilia business. The imposition of any such liability would be carefully evaluated by the company under the terms of the separation agreement. Government Matters On March 4, 2016, Biogen received a subpoena from the federal government for documents relating to Biogen’s relationship with non‑profit organizations that provide assistance to patients taking drugs sold by Biogen. On July 1, 2016, Biogen received civil investigative demands from the federal government for documents and information relating to Biogen’s treatment of certain service agreements with wholesalers when calculating and reporting Average Manufacturer Prices in connection with the Medicaid Drug Rebate Program.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies
Commitments and Contingencies	17. Commitments and Contingencies True North Therapeutics In connection with our acquisition of True North, the True North equityholders are eligible to receive additional payments of up to $425.0 million contingent on the achievement of future development, regulatory and sales milestones. See Note 3, Acquisition of True North Therapeutics, Inc. Contingent Development, Regulatory and Commercial Milestone Payments Based on our development plans primarily in gene editing and gene therapy for hemophilia and other blood disorders as of December 31, 2017, we could make potential future milestone payments to third party collaborators of up to approximately $755 million. Payments under these agreements generally become due and payable upon achievement of certain development, regulatory or commercial milestones. Because the achievement of these milestones had not occurred as of December 31, 2017, such contingencies have not been recorded in our financial statements. Amounts related to contingent milestone payments are not considered contractual obligations as they are contingent on the successful achievement of certain development, regulatory approval and commercial milestones. Leases We rent laboratory and office space under non-cancelable operating leases. These lease agreements contain various clauses for renewal at our option and, in certain cases, escalation clauses typically linked to rates of inflation. Rental expense under these leases amounted to $6.8 million in 2017. In addition to rent, the leases may require us to pay additional amounts for taxes, insurance, maintenance and other operating expenses. As of December 31, 2017, minimum rental commitments under non-cancelable leases for each of the next five years and total thereafter were as follows: (in millions) 2018 2019 2020 2021 2022 Thereafter Total Minimum lease payments $ 6.6 $ 6.7 $ 6.1 $ 6.0 $ 6.1 $ 24.9 $ 56.4

Guarantees

Guarantees	12 Months Ended
	Dec. 31, 2017
Guarantees
Guarantees	18. Guarantees As of December 31, 2017 and 2016, the company did not have significant liabilities recorded for guarantees. The company enters into indemnification provisions under agreements with other companies in the ordinary course of business, typically with business partners, contractors, clinical sites and customers. Under these provisions, the company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of our activities. These indemnification provisions generally survive termination of the underlying agreement. The maximum potential amount of future payments we could be required to make under these indemnification provisions is unlimited. However, to date the company has not incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. As a result, the estimated fair value of these agreements is minimal. Accordingly, the company has no liabilities recorded for these agreements as of December 31, 2017 and 2016.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Information
Segment Information	19. Segment Information We operate as one operating segment, which is discovering, researching, developing and commercializing innovative therapies for the treatment of rare blood disorders, and, therefore, our chief operating decision‑maker manages the operations of our company as a single operating segment. Enterprise‑wide disclosures about product revenues, other revenues and long‑lived assets by geographic area and information relating to major customers are presented below. Revenues are primarily attributed to individual countries based on location of the customer or licensee. Revenue by product is summarized as follows: For the Years Ended December 31, (In millions) 2017 2016 2015 United States ELOCTATE $ 615.6 $ 445.3 $ 308.3 ALPROLIX 290.1 267.9 208.8 Total product revenues $ 905.7 $ 713.2 $ 517.1 All Other Markets ELOCTATE $ 108.9 $ 67.7 $ 11.4 ALPROLIX 74.5 65.7 25.6 Total product revenues $ 183.4 $ 133.4 $ 37.0 Total ELOCTATE $ 724.5 $ 513.0 $ 319.7 ALPROLIX 364.6 333.6 234.4 Total product revenues $ 1,089.1 $ 846.6 $ 554.1 Geographic Inforrmation For the Years Ended December 31, (In millions) 2017 2016 2015 U.S. Product revenues from external customers $ 905.7 $ 713.2 $ 517.1 Revenue from collaborative partners $ 79.4 $ 40.8 $ 6.2 Long-lived assets $ 22.9 $ 27.7 $ 75.0 Japan Product revenues from external customers $ 138.8 $ 105.7 $ 37.0 Long-lived assets $ 0.8 $ 0.7 $ 0.5 Other Product revenues from external customers $ 44.6 $ 27.7 $ — Long-lived assets $ 0.3 $ — $ — Total Product revenues from external customers $ 1,089.1 $ 846.6 $ 554.1 Revenue from collaborative partners $ 79.4 $ 40.8 $ 6.2 Long-lived assets $ 24.0 $ 28.4 $ 75.5

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Data (Unaudited)
Quarterly Financial Data (Unaudited)	20. Quarterly Financial Data (Unaudited) First Second Third Fourth Total (in millions) Quarter Quarter Quarter Quarter Year 2017 Product revenue, net $ 242.0 $ 263.9 $ 274.8 $ 308.4 $ 1,089.1 Collaboration revenue 17.1 25.2 16.8 20.3 79.4 Total revenues 259.1 289.1 291.6 328.7 1,168.5 Gross profit(1) 195.8 208.6 226.1 258.4 888.9 Net income $ 69.3 $ 77.1 $ 67.9 $ 141.3 $ 355.6 First Second Third Fourth Total (in millions) Quarter Quarter Quarter Quarter Year 2016 Product revenue, net $ 182.8 $ 204.9 $ 217.1 $ 241.8 $ 846.6 Collaboration revenue 8.9 5.4 12.1 14.4 40.8 Total revenues 191.7 210.3 229.2 256.2 887.4 Gross profit(1) 159.2 152.1 157.7 180.5 649.5 Net income (loss) $ 66.7 $ 63.5 $ 80.5 $ 228.9 $ 439.6 (1) Gross profit is calculated as total revenues less cost of sales.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events
Subsequent Events	21. Subsequent Events Agreement and Plan of Merger On January 21, 2018, Bioverativ entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Sanofi (“Parent” or “Sanofi”), a French société anonyme , and Blink Acquisition Corp. (“Merger Sub”), a Delaware corporation and indirect wholly-owned subsidiary of Parent. The Board of Directors of the Company unanimously approved the Merger Agreement. Pursuant to the Merger Agreement, upon the terms and subject to the conditions thereof, Merger Sub commenced a tender offer on February 7, 2018 (the “Offer”), to acquire all of the outstanding shares of common stock of the Company, par value $0.001 per share (the “Shares”), at a purchase price of $105.0 per Share in cash, net of applicable withholding taxes and without interest (the “Offer Price”). The obligation of Merger Sub to purchase Shares tendered in the Offer is subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, including (i) that the number of Shares validly tendered and not withdrawn as of the expiration of the Offer, together with any Shares (if any) owned by Parent and its affiliates and excluding any Shares tendered pursuant to guaranteed delivery procedures that have not yet been “received” (as such term is defined in Section 251(h)(6)(f) of the Delaware General Corporation Law, as amended (“DGCL”)), represents at least a majority of the then outstanding Shares (the “Minimum Tender Condition”); (ii) (x) the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended and (y) that all consents of, and/or filings with, any governmental authority of competent jurisdiction or pursuant to any antitrust laws have been obtained and are in full force and effect and any applicable waiting period with respect thereto has expired; (iii) the absence of any law or order prohibiting the consummation of the Offer or the Merger; (iv) the accuracy of the Company’s representations and warranties (subject to customary materiality qualifiers); (v) the Company’s performance in all material respects of its obligations under the Merger Agreement; (vi) the absence, since the date of the Merger Agreement, of any fact, circumstance, condition, event, change, development, occurrence, result or event which, individually or in the aggregate, has had, or would reasonably be expected to have, a Company Material Adverse Effect (as defined in the Merger Agreement); (vii) the delivery to Parent and Merger Sub of a certificate, dated as of the expiration time of the Offer, certifying that the conditions in clauses (iv), (v) and (vi) have been satisfied; (viii) the Merger Agreement has not been terminated; and (ix) that the Company has received and delivered to Biogen and Parent a copy of the tax opinion required by a letter agreement dated January 21, 2018 between Biogen, Parent and the Company (the “Letter Agreement”) and the requirement that the Company deliver such tax opinion pursuant to the Tax Matters Agreement between Biogen and the Company dated January 31, 2017 has been satisfied pursuant to the Letter Agreement. These conditions are more specifically described in the Merger Agreement, which we filed as Exhibit 2.1 to the Company’s Current Report on Form 8-K filed with the SEC on January 22, 2018. As soon as practicable following (but on the same day as) the consummation of the Offer and subject to the satisfaction or waiver of certain conditions set forth in the Merger Agreement, Merger Sub will be merged with and into the Company (the “Merger”), with the Company surviving the Merger as an indirect wholly-owned subsidiary of Parent. The Merger will be governed by Section 251(h) of the DGCL and effected without a vote of the Company stockholders. As a result of the Merger, each Share (other than any Shares (i) owned by Parent, Merger Sub or any other direct or indirect wholly-owned subsidiary of Parent immediately prior to the Effective Time (as defined below) (other than Shares tendered and accepted for payment by Merger Sub in connection with the Offer), (ii) owned by the Company or held in the Company’s treasury immediately prior to the Effective Time, (iii) owned by any direct or indirect wholly-owned Subsidiary of the Company immediately prior to the Effective Time or (iv) issued and outstanding immediately prior to the Effective Time and held by a holder who is entitled to demand appraisal and who has properly exercised and perfected a demand for appraisal of such Shares in accordance with Section 262 of the DGCL and, as of the Effective Time, has neither effectively withdrawn nor lost such holder’s right to appraisal and payment under the DGCL with respect to such Shares) will (x) be converted automatically into the right to receive the Offer Price in cash, net of applicable withholding taxes and without interest and (y) cease to be outstanding and will automatically be cancelled and cease to exist and each holder of a certificate or a book-entry account statement representing any such Shares will have only the right to receive the Offer Price in accordance with the Merger Agreement. The Merger Agreement also provides that each Company stock option and Company restricted stock unit (collectively, the “Company Equity Awards”) that is outstanding as of immediately prior to the consummation of the Offer will accelerate and become fully vested and will be canceled and converted into the right to receive the Offer Price (less the applicable exercise price in the case of Company stock options) in cash (net of applicable withholding taxes and without interest) payable in respect of each Share subject to such Company Equity Award, except that the cash payment with respect to any Company restricted stock unit granted after the date of the Merger Agreement in accordance with the terms thereof to employees who are not executive officers will not be vested, and instead will remain outstanding and become vested and payable on December 31, 2018, subject to the employee’s continued employment with the Company or its affiliates, or upon any earlier termination without cause or constructive termination under the applicable severance plan. At or prior to the consummation of the Offer, the Company, its Board of Directors and the Compensation Committee of the Board of Directors, as applicable, are required to adopt resolutions and take any actions that are necessary to effectuate the provisions of the Merger Agreement with respect to the Company Equity Awards. In addition, pursuant to the Merger Agreement, the Company is required, among other things, to take all reasonable actions to terminate its 2017 Employee Stock Purchase Plan prior to the date that the Offer, the Merger and the other transactions contemplated by the Merger Agreement (collectively, the “Transactions”) close and to ensure no new offering period is commenced. The Merger Agreement includes representations and warranties, and covenants of the parties customary for a transaction of this nature. Until the earlier of the termination of the Merger Agreement and the date on which the Merger becomes effective (the “Effective Time”), the Company has agreed to operate its business and the business of its subsidiaries in the ordinary course, consistent with past practice, and has agreed to certain other restrictive operating covenants, as set forth more fully in the Merger Agreement. Subject to the terms and conditions of the Merger Agreement, the Company has also agreed not to solicit or engage in discussions with any third party regarding acquisition proposals. The Merger Agreement includes a remedy of specific performance for the Company, Parent and Merger Sub in the event one of the other parties breaches or fails to perform its obligations thereunder. The Merger Agreement also includes customary termination provisions for both the Company and Parent and provides that, in connection with the termination of the Merger Agreement under specified circumstances, including termination by the Company to accept and enter into a definitive agreement with respect to a “superior proposal” or by Parent in the event our Board of Directors changes its recommendation, the Company will be required to pay (or cause to be paid) a termination fee of $326.0 million (the “Termination Fee”). Any termination of the Merger Agreement by the Company in connection with a superior proposal is subject to certain conditions, including the Company’s compliance with certain procedures set forth in the Merger Agreement and a determination by our Board of Directors that the failure to take such action would reasonably be expected to be inconsistent with its fiduciary duties, payment of the Termination Fee by (or on behalf of) the Company and the concurrent execution of a definitive agreement by the Company with such third party. A “superior proposal” is defined in the Merger Agreement as a bona fide written “acquisition proposal”, which generally means a proposal made by a third party to acquire (x) 50% of the outstanding equity interests of the Company or (y) assets of the Company and/or its subsidiaries representing at least 50% of the fair market value of the assets of the Company and its subsidiaries, taken as a whole, that did not result from the Company’s breach of the non-solicitation provisions set forth in the Merger Agreement and that the Board of Directors determines in its good faith judgment (after consultation with its financial advisors and outside legal counsel) taking into account certain factors, is reasonably likely to be consummated in accordance with its terms and would, if consummated, result in a transaction that is more favorable to the Company’s stockholders from a financial point of view than the Transactions.

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Summary of Significant Accounting Policies
Reclassifications	Reclassifications Certain prior year amounts have been reclassified for consistency with the current period presentation. These reclassifications had no effect on the reported results of operations. In first quarter of 2017, the company concluded that it was appropriate to classify costs associated with medical affairs as research and development to better align with Bioverativ’s organizational structure. Previously, such costs had been classified as selling, general and administrative. As a result, the amounts that were previously presented in selling, general and administrative were reclassified in research and development for the years ended December 31, 2016 and 2015. For the Years Ended December 31, (In millions) 2016 2015 Medical reclassification $ 31.2 $ 50.8
Use of Estimates	Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments, and assumptions that may affect the reported amounts of assets, liabilities, equity, revenues and expenses, and related disclosure of contingent assets and liabilities. On an on-going basis we evaluate our estimates, judgments and methodologies. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets, liabilities and equity and the amount of revenues and expenses. Actual results may differ from these estimates under different assumptions or conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider only those investments which are highly liquid, readily convertible to cash and that mature within three months from date of purchase to be cash equivalents. The carrying values of money market funds approximate fair value due to their short-term maturities.
Accounts Receivable	Accounts Receivable The majority of accounts receivable arise from product sales and primarily represent amounts due from specialty pharmacies, hemophilia treatment centers, public and private hospitals and independent specialty distributors as well as contract manufacturing and royalty revenue from Sobi. The company monitors the financial performance and creditworthiness of its customers so that the company can properly assess and respond to changes in their credit profile. The company provides reserves against trade receivables for estimated losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are charged or written‑off against the reserve.
Concentration of Credit Risk	Concentration of Credit Risk CVS Health Corporation (CVS), a specialty pharmacy and ASD Specialty Healthcare (ASD), a specialty distributor, individually represent 13% and 12%, respectively, of outstanding accounts receivable for the year ended December 31, 2017; CVS, ASD and Accredo Health Incorporated, a specialty pharmacy, individually represent 24%, 14% and 11%, respectively, of outstanding accounts receivable for the year ended December 31, 2016. Other than these significant customers, concentration of credit risk with respect to receivables, which are typically unsecured, are largely mitigated due to the wide variety of customers. The majority of accounts receivable arise from product sales in the United States and Japan and have standard payment terms which generally require payment within 30 to 90 days. The company monitors the financial performance and creditworthiness of its customers so that the company can properly assess and respond to changes in their credit profile. The company continues to monitor these conditions and assess their possible impact on its business.
Inventory	Inventory Inventories are stated at the lower of cost or market with cost based on the first‑in, first‑out (FIFO) method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when selected for use in a clinical manufacturing campaign. Capitalization of Inventory Costs The company capitalizes inventory costs associated with its products prior to regulatory approval, when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. In determining whether or not to capitalize such costs, the company evaluates, among other factors, information regarding the drug candidate’s safety and efficacy, the status of regulatory submissions and communications with regulatory authorities and the outlook for commercial sales, including the existence of current or anticipated competitive drugs and the availability of reimbursement. In addition, the company evaluates risks associated with manufacturing the drug candidate and the remaining shelf‑life of the inventories. Obsolescence and Unmarketable Inventory The company periodically reviews its inventories for excess or obsolescence and write‑down obsolete or otherwise unmarketable inventory to its estimated net realizable value.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are carried at cost, subject to review for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. The cost of normal, recurring, or periodic repairs and maintenance activities related to property, plant and equipment are expensed as incurred. The cost for planned major maintenance activities, including the related acquisition or construction of assets, is capitalized if the repair will result in future economic benefits. Prior to the separation, Property, plant and equipment comprised of assets whereby a majority of its use was dedicated to the hemophilia business. The company generally depreciates or amortizes the cost of its property, plant and equipment using the straight‑line method over the estimated useful lives of the respective assets, which are summarized as follows: Asset Category Useful Lives Land Not depreciated Buildings 15 to 40 years Leasehold Improvements Lesser of the useful life or the term of the respective lease Furniture and Fixtures 5 to 7 years Machinery and Equipment 5 to 20 years Computer Software and Hardware 3 to 5 years
Acquired Intangibles	Acquired Intangibles Acquired intangibles include product rights, patents and in-process research and development (IPR&D) acquired in a business combination. IPR&D represents the fair value of research and development assets that have not reached technological feasibility. The value assigned to acquired IPR&D is determined by estimating the costs to develop the acquired technology into a commercial product, estimating revenue and costs associated with the product, adjusting the net cash flows for probability of success and discounting to present value. The estimated net cash flows consider the relevant market sizes and growth factors, expected trends in technology and the nature and expected timing of new product introductions by us and our competitors. The rates utilized to discount the net cash flows to their present value are commensurate with the stage of development of the projects and uncertainties in the economic estimates used in the projections. In estimating the probability of success, we utilize data regarding similar assets events from several sources, including industry studies and our own experience. Upon the acquisition of intangible assets, we complete an assessment of whether our acquisition constitutes the purchase of a single asset or a group of assets. We consider multiple factors in this assessment, including the nature of the technology acquired, the presence or absence of separate cash flows, the development process and stage of completion, quantitative significance and our rationale for entering into the transaction. If we acquire a business as defined under applicable accounting standards, then the acquired IPR&D is capitalized as an intangible asset. If we acquire an asset or group of assets that do not meet the definition of a business, then the acquired IPR&D is expensed on its acquisition date if it has no future alternative use. Future costs to develop these assets are recorded to research and development as they are incurred. We perform a qualitative assessment to determine whether any indicators for impairment exist. As a result of the assessment, the company concluded the carrying value of our acquired IPR&D exceeds its fair value. Acquired product rights and patents are recorded at fair value, assigned an estimated useful life, and are amortized over their estimated useful lives of approximately twelve years. See Note 9, Intangible Assets . Amortization is included in cost of sales in the consolidated statements of income.
Goodwill	Goodwill Goodwill represents the difference between the purchase price and the fair value of the identifiable tangible and intangible net assets when accounted for as a business combination using the purchase method of accounting. Goodwill is not amortized, but reviewed for impairment. Goodwill is reviewed annually and whenever events or changes in circumstances indicate that the carrying value of the goodwill might not be recoverable. We compare the fair value of our reporting unit to its carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of our reporting unit, then we would need to determine the implied fair value of our reporting unit’s goodwill. If the carrying value of our reporting unit’s goodwill exceeds its implied fair value, then we would record an impairment loss equal to the difference. As described above in Note 1, Nature of Business and Basis of Preparation , we operate in one operating segment which we consider our only reporting unit.
Impairment of Long Lived Assets	Impairment of Long‑Lived Assets Long‑lived assets to be held and used, including property, plant and equipment and definite‑lived intangible assets, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets or asset group may not be recoverable. Determination of recoverability is based on an estimate of undiscounted future cash flows resulting from the use of the asset and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written‑down to their fair values. Long‑lived assets to be disposed of are carried at fair value less costs to sell.
Contingent Consideration	Contingent Consideration The consideration for our acquisition includes future payments that are contingent upon the occurrence of various events. We recorded a liability for such contingent payments at fair value on the acquisition date. We estimated the fair value of contingent consideration through valuation models that incorporate probability-adjusted assumptions related to the likelihood of achieving the milestones and making related payments. Our contingent consideration is remeasured each reporting period. Changes in the fair value of our contingent consideration are recognized in our condensed consolidated statements of income. Changes in the fair value of the contingent consideration can result from changes to one or multiple inputs, including changes to the discount rates, changes in the probability of certain clinical events, regulatory approval, and the amount or timing of development and sales based milestones. Discount rates in our valuation models represent a measure of the weighted average cost of capital of the target associated with settling the liability. The period over which we discount our contingent consideration is based on the current development stage of the product candidates and our specific development plan for that product candidate. In estimating the probability of success, we utilize data regarding similar milestone events from several sources, including industry studies and our own experience. These fair value measurements are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the acquisition date and for each subsequent period. Accordingly, changes in assumptions could have a material impact on the amount of contingent consideration expense we record in any given period.
Non-designated Foreign Currency Contracts	Non-designated Foreign Currency Contracts Currency forward contracts are used as a part of our strategy to manage exposure related to foreign currency denominated monetary assets and liabilities. These currency forward contracts are not designated as cash flow, fair value or net investment hedges. The currency forward contracts are marked-to-market with changes in fair value recorded to other income (expense) and are entered into for periods consistent with currency transaction exposures, generally less than one year.
Translation of Foreign Currencies	Translation of Foreign Currencies The functional currency for the company’s non‑U.S. subsidiaries is their local currency. For non‑U.S. subsidiaries that transact in a functional currency other than the U.S. dollar, assets and liabilities are translated at current rates of exchange at the balance sheet date. Income and expense items are translated at the average foreign exchange rates for the period. Adjustments resulting from the translation of the financial statements of non‑U.S. operations into U.S. dollars are excluded from the determination of net income and are recorded in accumulated other comprehensive income, a separate component of equity.
Contingencies	Contingencies We are currently involved in various claims and legal proceedings. Loss contingency provisions are recorded if the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated or a range of loss can be determined. These accruals represent management’s best estimate of probable loss. Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. On a quarterly basis, we review the status of each significant matter and assess its potential financial exposure. Significant judgment is required in both the determination of probability and the determination as to whether an exposure is reasonably estimable. Because of uncertainties related to these matters, accruals are based only on the best information available at the time. As additional information becomes available, we reassess the potential liability related to pending claims and litigation and may change our estimates. These changes in the estimates of the potential liabilities could have a material impact on our consolidated results of operations and financial position.
Revenue Recognition	Revenue Recognition The company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the price to the customer is fixed or determinable; and collectability is reasonably assured. Product Revenues We sell mainly to specialty pharmacies, hemophilia treatment centers, public and private hospitals and independent specialty distributors. Any discounts offered to these customers are reflected as on‑invoice discounts. We also sell to specialty distributors who receive both on‑invoice discounts as well as chargebacks for sales to various U.S. government agencies such as U.S. Public Health Service (PHS). Provisions for rebates, chargebacks to distributors, and discounts are provided for at the time the related sales are recorded, and are reflected as a reduction of sales. Reserves established for these discounts and allowances are classified as reductions of accounts receivable (if the amount is payable to our customer) or a liability (if the amount is payable to a party other than our customer). Our estimates take into consideration our historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Actual amounts may ultimately differ from our estimates. If actual results vary, we adjust these estimates, which could have an effect on earnings in the period of adjustment. To date historical adjustments have not been material. Product revenue reserves are categorized as follows: discounts and contractual adjustments. Discounts include trade term discounts and volume discounts. Trade term discounts relate to estimated obligations for credits to be granted to customers for remitting payment on their purchases within established incentive periods. Volume discounts are earned as customers reach certain tier levels based upon their purchases. Contractual adjustments primarily relate to Medicaid and PHS discounts. Product returns are insignificant and mainly resulting from product damaged in transit or incorrectly shipped.
Collaborations	Collaborations Our development and commercialization arrangement with Sobi represents a collaborative arrangement because both Sobi and us are active participants and exposed to significant risks and rewards of the arrangement. Where we are the principal on sales transactions with third parties, we recognize revenue, cost of sales, including royalty cost of sales, and operating expenses on a gross basis in our income statement. We recognize payments between Sobi and us based upon their nature. These payments consist of royalty cost of sales, royalty revenue and contract manufacturing revenue. Royalty revenue and contract manufacturing revenue represent collaboration revenue in our income statement. See Note 4, Collaborations .
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Milestone payments prior to regulatory approval are expensed when the milestone is achieved. Payments made to counterparties on or after regulatory approval are capitalized and amortized over the remaining useful life of the related product. Amounts capitalized for such payments are included in acquired intangible assets, net of accumulated amortization. Also included in research and development expenses are allocations from Biogen. See Note 14, Related Parties.
Income Taxes	Income Taxes Deferred taxes are recognized for the future tax effects of temporary differences between financial and income tax reporting based on enacted tax laws and rates. With respect to uncertain tax positions, the company determines whether the position is more likely than not to be sustained upon examination, based on the technical merits of the position. Any tax position that meets the more‑likely‑than‑not recognition threshold is measured and recognized in the consolidated financial statements at the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement. The liability relating to uncertain tax positions is classified as current in the consolidated balance sheets to the extent the company anticipates making a payment within one year. Interest and penalties associated with income taxes are classified in the income tax expense line in the consolidated statements of income. Prior to the separation, the company’s income tax expense and deferred tax balances were calculated on a separate tax return basis although the company’s operations had historically been included in the tax returns filed by the respective Biogen entities, of which the company’s business was a part. For periods subsequent to the separation, Bioverativ files tax returns on its own behalf and its income tax expense and deferred income tax balances are recorded in accordance with the company’s standalone income tax positions. Biogen and Bioverativ entered into a tax matters agreement effective as of the date of separation.
Accounting for Share-Based Compensation	Accounting for Share‑Based Compensation In connection with the separation, we adopted our own share‑based compensation plans. Outstanding Biogen CSPUs, MSUs and PUs were converted to Bioverativ RSUs and outstanding Biogen stock options were converted to Bioverativ stock options. See Note 13, Share‑Based Compensation . We charge the estimated fair value of awards against income over the requisite service period, which is generally the vesting period. Where awards are made with non‑substantive vesting periods (for instance, where a portion of the award vests upon retirement eligibility), we estimate and recognize expense based on the period from the grant date to the date on which the employee is retirement eligible. We recognize forfeitures as they occur. The fair values of our stock option grants are estimated as of the date of grant using a Black‑Scholes option valuation model. The estimated fair values of the stock options are then expensed over the options’ vesting periods. The fair values of RSUs are based on the market value of our stock on the date of grant. Compensation expense for RSUs is recognized on a straight‑line basis over the applicable service period.
New Accounting Pronouncements	New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies that we adopt as of the specified effective date. The following new standards issued by FASB were adopted by the company on January 1, 2017: · Accounting Standards Update (ASU) No. 2015‑11, Inventory (Topic 330): Simplifying the Measurement of Inventory. The new standard applies only to inventory for which cost is determined by methods other than last-in, first-out and the retail inventory method, which includes inventory that is measured using first in, first out (FIFO) or average cost. Inventory within the scope of this standard is required to be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The adoption of this standard did not have a material impact on our financial position, results of operations or statements of cash flows upon adoption. · ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. The new standard requires that deferred tax assets and liabilities be classified as noncurrent in a classified statement of financial position. The adoption of this standard did not have a material impact on our financial position, results of operations or statements of cash flows upon adoption. · ASU No. 2016‑09, Compensation‑Stock Compensation (Topic 718): Improvements to Employee Share‑Based Payment Accounting. The new standard requires recognition of the income tax effects of vested or settled awards in the income statement and involves several other aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The adoption of this standard did not have a material impact on our financial position, results of operations or statements of cash flows upon adoption. In the fourth quarter of 2017 we adopted the following standard: · In January 2017 the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment. This new standard simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The adoption of this standard did not have a material impact on our financial position or results of operations. The following new standards have been issued by FASB but are not yet effective as of December 31, 2017: · In May 2014 the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The FASB has subsequently issued amendments to ASU No. 2014-09 that have the same effective date and transition date of January 1, 2018. We expect to adopt these standards using the full retrospective method. We will apply all of the requirements of the new standards to each comparative period presented in accordance with the requirements on accounting changes. We are finalizing our assessment of the effect of adoption. Based on this assessment, we expect changes in our revenue recognition policy relating to the opt-in consideration payable by Sobi to us under our collaboration agreement with Sobi (See Note 4, Collaborations ). Currently the payment by Sobi of the opt-in consideration is recognized over the term of the commercialization period using a cross-royalty payment structure. Upon adoption of these standards, for the year ended December 31, 2016, the net present value of the remaining opt-in consideration will be recognized as revenue and note receivable. Commencing in 2017, royalty revenue will be recognized at the contractual 12% rate rather than the effective rate of 13-15%. Royalty cost of sales will be recognized at the contractual rate of 12% in North America and 17% outside North America instead of the effective rate of 10-11% and 15-16%, respectively. Upon adoption in Q1 2018, our balance sheet at December 31, 2017 is expected to increase by approximately $190 million due to the note receivable from Sobi. · In January 2016 the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new standard amends certain aspects of accounting and disclosure requirements of financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in a company's results of operations. The new standard will be effective for us on January 1, 2018. The adoption of this standard is not expected to have a material impact on our financial position or results of operations. · In February 2016 the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires that all lessees recognize the assets and liabilities that arise from leases on their balance sheet and disclose qualitative and quantitative information about their leasing arrangements. The new standard will be effective for us on January 1, 2019. The adoption of this standard is not expected to have a material impact on our results of operations but may impact our financial position. · In October 2016 the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfer of Assets Other Than Inventory. This new standard eliminates the deferral of the tax effects of intra-entity transfers of an asset other than inventory. Under the new standard, entities should recognize the income tax consequences on an intra-entity transfer of an asset other than inventory when the transfer occurs. This new standard will be effective for us on January 1, 2018 and will be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of this standard is not expected to have a material impact on our financial position. · In November 2016 the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The amendments in this update require that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This new standard will be effective for us on January 1, 2018. The adoption of this standard is not expected to have a material impact on our financial position. · In January 2017 the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This new standard clarifies the definition of a business and provides a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set of assets and activities is not a business. This new standard will be effective for us on January 1, 2018, however early adoption is permitted. The adoption of this standard is not expected to have a material impact on our financial position. In May 2017 the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting. This new standard provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. This new standard will be effective for us on January 1, 2018. The adoption of this standard is not expected to have a material impact on our financial position or results of operations.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Significant Accounting Policies
Schedule of reclassification	For the Years Ended December 31, (In millions) 2016 2015 Medical reclassification $ 31.2 $ 50.8
Schedule of plant and equipment's useful life	Asset Category Useful Lives Land Not depreciated Buildings 15 to 40 years Leasehold Improvements Lesser of the useful life or the term of the respective lease Furniture and Fixtures 5 to 7 years Machinery and Equipment 5 to 20 years Computer Software and Hardware 3 to 5 years

Acquisition of True North The30

Acquisition of True North Therapeutics, Inc. (Tables)	12 Months Ended
	Dec. 31, 2017
Acquisition of True North Therapeutics, Inc.
Schedule of purchase price consideration	(In millions) Estimated Fair Value Cash paid, net of cash acquired $ 395.7 Contingent consideration 188.5 Total purchase price consideration $ 584.2
Schedule of purchase price allocation	As of December 31, (In millions) 2017 Current assets $ 0.6 Property, plant and equipment, net 0.6 In-process research and development (IPR&D) 590.0 Goodwill 170.7 Accounts payable and accrued expenses (4.0) Deferred tax liabilities (173.7) Final fair value of identifiable assets acquired and liabilities assumed $ 584.2
Schedule of goodwill	(In millions) Balance at December 31, 2016 $ — Additions 170.7 Balance at December 31, 2017 $ 170.7
Schedule of pro forma information	For the Years Ended December 31, (In millions, except per share amounts) 2017 2016 Revenues $ 1,168.6 $ 887.4 Net income 341.0 407.7 Per share amounts: Net income per share - basic 3.15 3.78 Net income per share - diluted 3.14 3.78

Financial instruments and fai31

Financial instruments and fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Financial instruments and fair value measurements
Schedule of fair value of assets and liabilities	As of December 31, 2017 (In millions) Total Quoted Prices Significant Other Significant Assets Cash equivalents $ 411.1 $ — $ 411.1 $ — Plan assets for deferred compensation 18.7 — 18.7 — Derivative contracts 1.1 — 1.1 — Total $ 430.9 $ — $ 430.9 $ — Liabilities Derivative contracts 0.7 — 0.7 — Contingent consideration obligations $ 198.4 $ — $ — $ 198.4 Total $ 199.1 $ — $ 0.7 $ 198.4
Schedule of rollforward of contingent consideration obligations	(In millions) Balance at December 31, 2016 $ — Additions 188.5 Research and development expenses recognized due to change in fair value 9.9 Balance at December 31, 2017 $ 198.4

Reserves for Discounts and Al32

Reserves for Discounts and Allowances (Tables)	12 Months Ended
	Dec. 31, 2017
Reserves for Discounts and Allowances
Schedule of analysis of the change in reserves	Contractual (In millions) Discounts Adjustments Returns Total Balance at December 31, 2015 $ 5.8 $ 16.0 — $ 21.8 Provision related to current period sales 160.9 165.2 1.3 327.4 Adjustment related to prior period sales (2.0) (0.7) — (2.7) Credits/payments made (158.7) (154.0) (1.0) (313.7) Balance at December 31, 2016 $ 6.0 $ 26.5 0.3 $ 32.8 Provision related to current period sales 178.0 304.1 0.7 482.8 Adjustment related to prior period sales (1.3) 3.2 0.3 2.2 Credits/payments made (176.9) (282.2) (0.3) (459.4) Balance at December 31, 2017 $ 5.8 $ 51.6 $ 1.0 $ 58.4 As of December 31, (In millions) 2017 2016 Reduction of accounts receivable $ 10.5 $ 11.1 Current liability 47.9 21.7 Total reserves $ 58.4 $ 32.8

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory
Schedule of components of inventory	As of December 31, (In millions) 2017 2016 Raw materials $ 0.4 $ 42.9 Work in process 11.4 227.2 Finished goods 28.8 31.9 Total inventory $ 40.6 $ 302.0

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Intangible Assets
Schedule of intangible assets, net of accumulated amortization	As of As of December 31, 2017 December 31, 2016 Estimated Accumulated Accumulated (In millions except for estimated life) Life Cost Amortization Net Cost Amortization Net Developed technology 11 years $ 61.7 $ (15.8) $ 45.9 $ 61.7 $ (10.0) $ 51.7 IPR&D Indefinite 590.0 — 590.0 — — — Total $ 651.7 $ (15.8) $ 635.9 $ 61.7 $ (10.0) $ 51.7

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment
Schedule of components of property, plant and equipment	As of December 31, (In millions) 2017 2016 Buildings $ — $ 8.0 Leasehold improvements 8.7 — Machinery and equipment 30.8 21.0 Computer software and hardware 6.6 5.9 Furniture and fixtures 0.9 0.5 Construction in progress 1.4 6.9 Total cost 48.4 42.3 Less: accumulated depreciation 24.4 13.9 Total property, plant and equipment, net $ 24.0 $ 28.4

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes
Schedule of income before income tax provision and income tax expense	For the Years Ended December 31, (In millions) 2017 2016 2015 Income (loss) before income tax expense (benefit): Domestic $ 444.0 $ 284.1 $ 94.2 Foreign 7.9 7.8 4.4 Total $ 451.9 $ 291.9 $ 98.6 Income tax expense (benefit): Current Domestic $ 140.8 $ 8.4 $ — Foreign 3.1 2.4 1.4 Deferred Domestic (47.3) (158.5) (11.4) Foreign (0.3) — — Total income tax expense (benefit) $ 96.3 $ (147.7) $ (10.0)
Schedule of deferred tax assets and liabilities	As of December 31, (In millions) 2017 2016 Deferred tax assets Net operating loss $ 21.6 $ 85.5 Tax credits 3.6 57.4 Inventory, other reserves, and accruals 12.8 14.5 Share-based compensation 6.7 3.4 Intangibles, net — 9.5 Deferred revenue 9.2 3.6 Other 1.2 — Valuation allowance — — Total deferred tax assets $ 55.1 $ 173.9 Deferred tax liabilities Purchased intangible assets $ (140.4) $ (16.3) Depreciation and amortization, net (2.7) (3.4) Total deferred tax liabilities $ (143.1) $ (19.7)
Schedule of effective tax rate reconciliation	For the Years Ended December 31, 2017 2016 2015 Statutory rate 35.0 % 35.0 % 35.0 % State taxes 2.1 0.8 1.0 Taxes on foreign earnings — (0.1) (0.3) Tax rate change (13.0) — — Credits and NOLs (5.5) (0.7) (3.0) Changes in valuation allowance — (84.8) (42.7) Other permanent items 2.2 (1.3) (0.2) Other 0.5 0.5 — Effective income tax rate 21.3 % (50.6) % (10.2) %

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings per Share
Schedule of basic and diluted earnings per share	For the Years Ended December 31, (In millions) 2017 2016 2015 Numerator: Net income $ 355.6 $ 439.6 $ 108.6 Denominator: Weighted average number of common shares outstanding 108.1 108.0 108.0 Effect of dilutive securities: Stock options — — — Time-vested restricted stock units 0.4 — — Dilutive potential common shares 0.4 — — Shares used in calculating diluted earnings per share 108.5 108.0 108.0

Share Based Compensation (Table

Share Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Share Based Compensation
Schedule of share-based compensation expense	For the Years Ended December 31, (In millions) 2017 2016 2015 Cost of sales $ — $ 7.3 $ 2.1 Research and development 5.0 3.7 4.8 Selling, general and administrative 27.0 4.3 6.3 Total share-based compensation expense $ 32.0 $ 15.3 $ 13.2
Schedule of option valuation assumptions	For the Years Ended December 31, 2017 Expected volatility 40.0% Range of expected life (in years) 4 ̶ 5 Range of risk-free interest rate 1.72% ̶ 2.13% Dividend yield ̶ Range of fair value per stock option $16.78 ̶ $23.38
Schedule of stock option activity	Weighted Average Per Share Grant (In thousands, except per share amounts) Shares Date Fair Value Outstanding at December 31, 2016 — $ — Granted 2,254.5 16.98 Exercised — — Cancelled (91.2) 17.61 Outstanding at December 31, 2017 2,163.3 $ 16.97
Schedule of RSU activity	Weighted Average Per Share Grant (In thousands, except per share amounts) Shares Date Fair Value Unvested at December 31, 2016 348.6 $ 46.86 Granted 401.4 46.79 Conversions 337.4 44.98 Vested (227.5) 47.69 Forfeited (55.2) 46.30 Unvested at December 31, 2017 804.7 $ 45.84
Schedule of restricted stock units conversions	(In thousands) Shares RSUs converted from MSUs 155.0 RSUs converted from CSPUs 43.6 RSUs converted from PUs 138.8 Total 337.4
Schedule of MSU valuation assumptions	For the Years Ended December 31, 2016 2015 Expected dividend yield ̶ ̶ Range of expected stock price volatility 38.2% - 40.7% 31.0% - 33.2% Range of risk-free interest rates 0.6% - 0.9% 0.2% - 1.0% 30 calendar day average stock price on grant date $260.67 - $304.86 $277.35 - $426.27 Weighted-average per share grant date fair value $326.65 $499.25

Related Parties (Tables)

Related Parties (Tables)	12 Months Ended
	Dec. 31, 2017
Related Parties
Schedule of corporate overhead and other allocations from Biogen	For the Years Ended December 31, (In millions) 2017 2016 2015 Research and development allocations $ 6.5 $ 88.7 $ 84.5 Selling, general and administrative allocations 5.1 60.7 64.0 Other (income) expense, net allocations 0.2 0.6 0.1 Total corporate overhead and other allocations from Biogen $ 11.8 $ 150.0 $ 148.6

Other Consolidated Financial 40

Other Consolidated Financial Statement Detail (Tables)	12 Months Ended
	Dec. 31, 2017
Other Consolidated Financial Statement Detail
Schedule of accrued expenses and other	As of December 31, (In millions) 2017 2016 Revenue-related rebates $ 47.9 $ 21.7 Employee compensation and benefits 52.4 15.9 Research and development 9.9 5.5 Royalty and collaboration 38.8 26.6 Short-term portion of contingent consideration 49.2 — Taxes payable 9.4 10.8 Other 25.9 8.8 Total accrued expenses and other current liabilities $ 233.5 $ 89.3
Long-Term Liabilities	As of December 31, (In millions) 2017 2016 Employee compensation and benefits $ — $ 18.7 Sobi payments 87.8 45.0 Other 4.7 — Total long term liabilities $ 92.5 $ 63.7

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies
Schedule of minimum rental commitments	As of December 31, 2017, minimum rental commitments under non-cancelable leases for each of the next five years and total thereafter were as follows: (in millions) 2018 2019 2020 2021 2022 Thereafter Total Minimum lease payments $ 6.6 $ 6.7 $ 6.1 $ 6.0 $ 6.1 $ 24.9 $ 56.4

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Information
Schedule of revenue by product	For the Years Ended December 31, (In millions) 2017 2016 2015 United States ELOCTATE $ 615.6 $ 445.3 $ 308.3 ALPROLIX 290.1 267.9 208.8 Total product revenues $ 905.7 $ 713.2 $ 517.1 All Other Markets ELOCTATE $ 108.9 $ 67.7 $ 11.4 ALPROLIX 74.5 65.7 25.6 Total product revenues $ 183.4 $ 133.4 $ 37.0 Total ELOCTATE $ 724.5 $ 513.0 $ 319.7 ALPROLIX 364.6 333.6 234.4 Total product revenues $ 1,089.1 $ 846.6 $ 554.1
Schedule of geographic information	For the Years Ended December 31, (In millions) 2017 2016 2015 U.S. Product revenues from external customers $ 905.7 $ 713.2 $ 517.1 Revenue from collaborative partners $ 79.4 $ 40.8 $ 6.2 Long-lived assets $ 22.9 $ 27.7 $ 75.0 Japan Product revenues from external customers $ 138.8 $ 105.7 $ 37.0 Long-lived assets $ 0.8 $ 0.7 $ 0.5 Other Product revenues from external customers $ 44.6 $ 27.7 $ — Long-lived assets $ 0.3 $ — $ — Total Product revenues from external customers $ 1,089.1 $ 846.6 $ 554.1 Revenue from collaborative partners $ 79.4 $ 40.8 $ 6.2 Long-lived assets $ 24.0 $ 28.4 $ 75.5

Quarterly Financial Data (Una43

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Data (Unaudited)
Schedule of quarterly financial data	First Second Third Fourth Total (in millions) Quarter Quarter Quarter Quarter Year 2017 Product revenue, net $ 242.0 $ 263.9 $ 274.8 $ 308.4 $ 1,089.1 Collaboration revenue 17.1 25.2 16.8 20.3 79.4 Total revenues 259.1 289.1 291.6 328.7 1,168.5 Gross profit(1) 195.8 208.6 226.1 258.4 888.9 Net income $ 69.3 $ 77.1 $ 67.9 $ 141.3 $ 355.6 First Second Third Fourth Total (in millions) Quarter Quarter Quarter Quarter Year 2016 Product revenue, net $ 182.8 $ 204.9 $ 217.1 $ 241.8 $ 846.6 Collaboration revenue 8.9 5.4 12.1 14.4 40.8 Total revenues 191.7 210.3 229.2 256.2 887.4 Gross profit(1) 159.2 152.1 157.7 180.5 649.5 Net income (loss) $ 66.7 $ 63.5 $ 80.5 $ 228.9 $ 439.6 Gross profit is calculated as total revenues less cost of sales.

Nature of Business and Basis 44

Nature of Business and Basis of Preparation (Details)	Feb. 01, 2017	Dec. 31, 2017segment
Number of shares issued in exchange of Biogen common stock held	1
Number of operating segments		1
Biogen
Number of shares issued in exchange of Biogen common stock held	2

Summary of Significant Accoun45

Summary of Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Research and development	$ 224.6	$ 210.1	$ 236.9
Acquired intangibles useful life	12 years
Number of operating segments | segment	1
Minimum | Buildings
Property plant and equipment useful life	15 years
Minimum | Furniture and fixtures
Property plant and equipment useful life	5 years
Minimum | Machinery and equipment
Property plant and equipment useful life	5 years
Minimum | Computer software and hardware
Property plant and equipment useful life	3 years
Maximum | Buildings
Property plant and equipment useful life	40 years
Maximum | Furniture and fixtures
Property plant and equipment useful life	7 years
Maximum | Machinery and equipment
Property plant and equipment useful life	20 years
Maximum | Computer software and hardware
Property plant and equipment useful life	5 years
Reclassification
Research and development		$ 31.2	$ 50.8
Accounts Receivable | Credit Concentration | CVS
Concentration credit risk	13.00%	24.00%
Accounts Receivable | Credit Concentration | ASD
Concentration credit risk	12.00%	14.00%
Accounts Receivable | Credit Concentration | Accredo Health
Concentration credit risk		11.00%

Summary of Significant Accoun46

Summary of Significant Accounting Policies (ASU) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2014
ASU No. 2014-09
New Accounting Pronouncements
Contractual royalty rate	12.00%
Bioverativ North American Territory | ASU No. 2014-09
New Accounting Pronouncements
Contractual royalty cost of sales (as a percent)	12.00%
Bioverativ other than North American Territory | ASU No. 2014-09
New Accounting Pronouncements
Contractual royalty cost of sales (as a percent)	17.00%
Minimum
New Accounting Pronouncements
Revenue effective royalty (as a percent)	13.00%
Minimum | Bioverativ North American Territory
New Accounting Pronouncements
Cost of sales effective royalty (as a percent)	10.00%
Minimum | Bioverativ other than North American Territory
New Accounting Pronouncements
Cost of sales effective royalty (as a percent)	15.00%
Maximum
New Accounting Pronouncements
Revenue effective royalty (as a percent)	15.00%
Maximum | Bioverativ North American Territory
New Accounting Pronouncements
Cost of sales effective royalty (as a percent)	11.00%
Maximum | Bioverativ other than North American Territory
New Accounting Pronouncements
Cost of sales effective royalty (as a percent)	16.00%
Sobi
New Accounting Pronouncements
Contractual royalty rate			12.00%
Revenue effective royalty (as a percent)	14.00%
Cost of sales effective royalty (as a percent)	11.00%	10.00%
Sobi | ASU No. 2014-09 | Forecast adjustment
New Accounting Pronouncements
Note receivable	$ 190
Sobi | Bioverativ North American Territory
New Accounting Pronouncements
Contractual royalty cost of sales (as a percent)			7.00%

Acquisition of True North The47

Acquisition of True North Therapeutics, Inc. (Details) - USD ($) $ in Millions	Jun. 28, 2017	Dec. 31, 2017
Business combinations
Potential future milestone payments		$ 755
Purchase price consideration
Cash paid, net of cash acquired		395.7
Purchase price allocation
Goodwill		170.7
True North
Business combinations
Consideration paid, plus assumed cash	$ 395.7
Potential future milestone payments	$ 425
Purchase price consideration
Cash paid, net of cash acquired		395.7
Contingent consideration		188.5
Total purchase price consideration		584.2
Purchase price allocation
Current assets		0.6
Property, plant and equipment, net		0.6
In-process research and development (IPR&D)		590
Goodwill		170.7
Accounts payable and accrued expenses		(4)
Deferred tax liabilities		(173.7)
Final fair value of identifiable assets acquired and liabilities assumed		$ 584.2
Discount rate (as a percent)	18.00%

Acquisition of True North The48

Acquisition of True North Therapeutics, Inc. (Goodwill and Contingency) (Details) - USD ($) $ in Millions	Jun. 28, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill
Goodwill, ending balance		$ 170.7
Potential future milestone payments		755
Contingent consideration fair value		198.4	$ 0
Remeasurement of contingent consideration		9.9
True North
Goodwill
Additions		170.7
Goodwill, ending balance		170.7
Potential future milestone payments	$ 425
Contingent consideration fair value	188.5
Remeasurement of contingent consideration		9.9
Amount held in escrow	$ 40
Indemnification obligation period	18 months
Acquisition and integration costs		$ 9

Acquisition of True North The49

Acquisition of True North Therapeutics, Inc. (Proforma) (Details) - True North - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pro forma information
Revenue	$ 1,168.6	$ 887.4
Net (loss)/income	$ 341	$ 407.7
Net (loss)/income per share - basic (in dollars per share)	$ 3.15	$ 3.78
Net (loss)/income per share - diluted (in dollars per share)	$ 3.14	$ 3.78
Acquisition and integration costs	$ 9
Integration and acquisition cost adjustment
Pro forma information
Acquisition and integration costs	$ 11.6

Collaborations (Details)

Collaborations (Details) $ in Millions

1 Months Ended

3 Months Ended

12 Months Ended

Aug. 31, 2017USD ($)item

Feb. 28, 2017USD ($)

Jul. 31, 2015USD ($)

Nov. 30, 2014USD ($)

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

May 31, 2016USD ($)

Nov. 30, 2015USD ($)

Jan. 31, 2014USD ($)

Jan. 31, 2007

Collaborations

Revenue from collaborative partners

$ 20.3

$ 16.8

$ 25.2

$ 17.1

$ 14.4

$ 12.1

$ 5.4

$ 8.9

$ 79.4

$ 40.8

$ 6.2

Potential future milestone payments

$ 755

$ 755

Sobi

Collaborations

Shared manufacturing and development expense reimbursement rate (as a percent)

50.00%

Post regulatory approval period

90 days

Exclusive development expense reimbursement rate (as a percent)

100.00%

Reimbursement Period

6 years

Period all reimbursement must be paid after Reimbursement Period

90 days

Royalty payable and receivable (as a percent)

12.00%

Royalty payable increase after Reimbursement Period (as a percent)

5.00%

Cost of sales effective royalty (as a percent)

11.00%

10.00%

Royalty receivable during Reimbursement Period (as a percent)

17.00%

Revenue effective royalty (as a percent)

14.00%

14.00%

Sangamo

Collaborations

Potential future milestone payments

$ 215

Bicycle

Collaborations

Potential future milestone payments

$ 410

Number of programs | item

3

Upfront payment

$ 10

Bioverativ North American Territory | Sobi

Collaborations

Royalty payable during Reimbursement Period (as a percent)

7.00%

Bioverativ Direct Territory | Sobi

Collaborations

Royalty payable during Reimbursement Period (as a percent)

12.00%

ALPROLIX | Sobi

Collaborations

Proceeds from agreement

$ 10

Aggregate amount reimbursable

$ 97.4

$ 97.4

$ 184.7

ELOCTA | Sobi

Collaborations

Proceeds from agreement

$ 10

Aggregate amount reimbursable

$ 90.5

$ 90.5

$ 211

BIVV002 | Sobi

Collaborations

Revenue from collaborative partners

$ 6.2

Biogen | Syntonix

Collaborations

Ownership acquired (as a percent)

100.00%

Debt and Credit Agreements (Det

Debt and Credit Agreements (Details) - Credit Facility $ in Millions	Jun. 28, 2017USD ($)	Dec. 31, 2017USD ($)
Debt and credit agreements
Maximum borrowing capacity	$ 175
Borrowings outstanding		$ 0
Leverage ratio	3
Leverage ratio upon consummation of a material acquisition	4
Leverage ratio step down after each full fiscal quarter	0.25
Interest coverage ratio	3
Minimum | Base rate
Debt and credit agreements
Variable interest margin (as a percent)	0.50%
Minimum | Eurocurrency rate
Debt and credit agreements
Variable interest margin (as a percent)	1.50%
Maximum | Base rate
Debt and credit agreements
Variable interest margin (as a percent)	1.00%
Maximum | Eurocurrency rate
Debt and credit agreements
Variable interest margin (as a percent)	2.00%

Financial instruments and fai52

Financial instruments and fair value measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Liabilities
Contingent consideration obligations	$ 198.4	$ 0
Foreign currency
Liabilities
Hedged foreign currency derivative gain (loss)	2.2	$ 0
Foreign currency | Undesignated Hedge
Liabilities
Notional amount	123.1
Recurring
Assets
Cash equivalents	411.1
Plan assets for deferred compensation	18.7
Derivative contracts	1.1
Total	430.9
Liabilities
Derivative contracts	0.7
Contingent consideration obligations	198.4
Total	199.1
Level 2 | Recurring
Assets
Cash equivalents	411.1
Plan assets for deferred compensation	18.7
Derivative contracts	1.1
Total	430.9
Liabilities
Derivative contracts	0.7
Total	0.7
Level 3 | Recurring
Liabilities
Contingent consideration obligations	198.4
Total	$ 198.4

Financial instruments and fai53

Financial instruments and fair value measurements (Contingent Consideration) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Financial instruments and fair value measurements
Balance, beginning	$ 0
Additions	188.5
Research and development expenses recognized due to change in fair value	9.9
Balance, ending	$ 198.4

Reserves for Discounts and Al54

Reserves for Discounts and Allowances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reserve rollforward
Balance at beginning of period	$ 32.8	$ 21.8
Provision related to current period sales	482.8	327.4
Adjustment related to prior period sales	2.2	(2.7)
Credits/payments made	(459.4)	(313.7)
Balance at end of period	58.4	32.8
Discounts
Reserve rollforward
Balance at beginning of period	6	5.8
Provision related to current period sales	178	160.9
Adjustment related to prior period sales	(1.3)	(2)
Credits/payments made	(176.9)	(158.7)
Balance at end of period	5.8	6
Contractual Adjustments
Reserve rollforward
Balance at beginning of period	26.5	16
Provision related to current period sales	304.1	165.2
Adjustment related to prior period sales	3.2	(0.7)
Credits/payments made	(282.2)	(154)
Balance at end of period	51.6	26.5
Returns
Reserve rollforward
Balance at beginning of period	0.3
Provision related to current period sales	0.7	1.3
Adjustment related to prior period sales	0.3
Credits/payments made	(0.3)	(1)
Balance at end of period	$ 1	$ 0.3

Reserves for Discounts and Al55

Reserves for Discounts and Allowances (Summary) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reserves for Discounts and Allowances
Reduction of accounts receivable	$ 10.5	$ 11.1
Current liability	47.9	21.7
Total reserves	$ 58.4	$ 32.8	$ 21.8

Inventory (Details)

Inventory (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Raw materials	$ 0.4	$ 42.9
Work in process	11.4	227.2
Finished goods	28.8	31.9
Total inventory	40.6	302
Inventory written down	8.8	$ 13.5	$ 1.3
Biogen
Inventory retained by Biogen	$ 179

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible assets
Estimated Life	12 years
Finite-lived intangible assets, amortization	$ (15.8)	$ (10)
Intangible assets, cost	651.7	61.7
Intangible assets, net	635.9	51.7
Amortization expense associated with acquired intangible assets	5.8	$ 4.8	$ 3
In-process research and development (IPR&D)
Intangible assets
Indefinite-lived intangible assets	$ 590
Developed technology
Intangible assets
Estimated Life	11 years	11 years
Finite-lived intangible assets, cost	$ 61.7	$ 61.7
Finite-lived intangible assets, amortization	(15.8)	(10)
Finite-lived intangible assets, net	$ 45.9	$ 51.7

Property, Plant and Equipment58

Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, plant and equipment
Total cost	$ 48.4	$ 42.3
Less: accumulated depreciation	24.4	13.9
Total property, plant and equipment, net	24	28.4	$ 75.5
Depreciation expense associated with property, plant and equipment	8.7	48.6	$ 12.6
Buildings
Property, plant and equipment
Total cost		8
Leasehold improvements
Property, plant and equipment
Total cost	8.7
Machinery and equipment
Property, plant and equipment
Total cost	30.8	21
Computer software and hardware
Property, plant and equipment
Total cost	6.6	5.9
Furniture and fixtures
Property, plant and equipment
Total cost	0.9	0.5
Construction in progress
Property, plant and equipment
Total cost	1.4	$ 6.9
Biogen
Property, plant and equipment
Property, plant and equipment retained by Biogen	$ 9.8

Income Taxes (2017 Tax Act) (De

Income Taxes (2017 Tax Act) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statutory rate (as a percent)		35.00%	35.00%	35.00%
Net reduction in income tax expense due to Tax Cuts and Jobs Act		$ (58.8)
Forecast
Statutory rate (as a percent)	21.00%

Income Taxes (Tax Provision and

Income Taxes (Tax Provision and Deferred) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (loss) before income taxes expense (benefit):
Domestic	$ 444	$ 284.1	$ 94.2
Foreign	7.9	7.8	4.4
Income before income tax expense (benefit)	451.9	291.9	98.6
Current
Domestic	140.8	8.4
Foreign	3.1	2.4	1.4
Deferred
Domestic	(47.3)	(158.5)	(11.4)
Foreign	(0.3)
Total income tax expense (benefit)	96.3	(147.7)	$ (10)
Deferred tax assets
Net operating loss	21.6	85.5
Tax credits	3.6	57.4
Inventory, other reserves, and accruals	12.8	14.5
Share-based compensation	6.7	3.4
Intangibles, net		9.5
Deferred revenue	9.2	3.6
Other	1.2
Total deferred tax assets	55.1	173.9
Deferred tax liabilities
Purchased intangible assets	(140.4)	(16.3)
Depreciation and amortization, net	(2.7)	(3.4)
Total deferred tax liabilities	(143.1)	$ (19.7)
Intercompany prepaid tax and deferred charges	$ 26

Income Taxes (Income Tax Reconc

Income Taxes (Income Tax Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense Reconciliation
Statutory rate (as a percent)	35.00%	35.00%	35.00%
State taxes (as a percent)	2.10%	0.80%	1.00%
Taxes on foreign earnings (as a percent)		(0.10%)	(0.30%)
Tax rate change (as a percent)	(13.00%)
Credits and NOLs (as a percent)	(5.50%)	(0.70%)	(3.00%)
Changes in valuation allowance (as a percent)		(84.80%)	(42.70%)
Other permanent items (as a percent)		(1.30%)	(0.20%)
Other permanent items increase (as a percent)	2.20%
Other (as a percent)	0.50%	0.50%
Effective income tax rate (as a percent)	21.30%	(50.60%)	(10.20%)
Increase (decrease) valuation allowance deferred tax assets		$ (247.3)

Income Taxes (Carryforward) (De

Income Taxes (Carryforward) (Details) $ in Millions	Dec. 31, 2017USD ($)
Federal
Carry forward
Net operating losses carry forward	$ 68.8
State
Carry forward
Net operating losses carry forward	102.3
General business credit | Federal
Carry forward
Tax credit carry forwards	$ 4

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) shares in Millions, $ in Millions	Feb. 01, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net income		$ 141.3	$ 67.9	$ 77.1	$ 69.3	$ 228.9	$ 80.5	$ 63.5	$ 66.7	$ 355.6	$ 439.6	$ 108.6
Denominator:
Weighted average number of common shares outstanding (in shares)										108.1	108	108
Effect of dilutive securities:
Dilutive potential common shares (in shares)										0.4
Shares used in calculating diluted earnings per share (in shares)										108.5	108	108
Shares excluded in computation of diluted EPS (in shares)										2.2	2.5	2.5
Biogen
Issuance of common stock upon separation (in shares)	108
RSUs
Effect of dilutive securities:
Effect of share-based awards										0.4

Share Based Compensation (Detai

Share Based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based compensation
Term of awards	10 years
Share based compensation expense	$ 32	$ 15.3	$ 13.2
Cost of sales
Share-based compensation
Share based compensation expense		7.3	2.1
Research and development
Share-based compensation
Share based compensation expense	5	3.7	4.8
Selling, general and administrative
Share-based compensation
Share based compensation expense	$ 27	$ 4.3	$ 6.3
RSUs
Share-based compensation
Maximum shares available	2,250,000
Employee Stock Purchase Plan
Share-based compensation
Maximum shares available	1,625,000

Share Based Compensation (Optio

Share Based Compensation (Options) (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Jan. 21, 2018
Share-based compensation
Vesting percentage	33.30%
Vesting period	3 years
Assumptions
Expected volatility (as a percent)	40.00%
Risk-free interest rate, minimum (as a percent)	1.72%
Risk-free interest rate, maximum (as a percent)	2.13%
Dividend yield (as a percent)	0.00%
Unrecognized compensation for unvested stock options	$ 19.8
Recognition period for unvested awards	2 years 2 months 12 days
Options exercisable (in shares)	0
Stock option activity (in shares)
Granted (in shares)	2,254,500
Cancelled (in shares)	(91,200)
Outstanding, ending (in shares)	2,163,300
Stock option activity (weighted average)
Granted (in dollars per shares)	$ 16.98
Cancelled (in dollars per shares)	17.61
Outstanding, ending (in dollars per shares)	$ 16.97
Minimum
Assumptions
Range of expected life	4 years
Fair value (in dollars per share)	$ 16.78
Maximum
Assumptions
Range of expected life	5 years
Fair value (in dollars per share)	$ 23.38
Sanofi
Stock option activity (weighted average)
Purchase price (in dollars per share)		$ 105

Share Based Compensation (NonOp

Share Based Compensation (NonOptions) (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 01, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 21, 2018
RSUs
Share-based compensation
Unrecognized compensation for unvested RSUs		$ 13.8
Recognition period for unvested awards		1 year 4 months 24 days
Non-option activity (in shares)
Unvested, beginning (in shares)		348,600
Granted (in shares)		401,400
Conversion (in shares)	337,400	337,400
Vested (in shares)		(227,500)
Forfeited (in shares)		(55,200)
Unvested, ending (in shares)		804,700	348,600
Non-option activity (weighted average)
Unvested, beginning (in dollars per shares)		$ 46.86
Granted (in dollars per shares)		46.79
Conversion (in dollars per share)		44.98
Vested (in dollars per shares)		47.69
Forfeited (in dollars per shares)		46.30
Unvested, ending (in dollars per shares)		$ 45.84	$ 46.86
MSU
Non-option activity (in shares)
Conversion (in shares)	155,000
CSPU
Non-option activity (in shares)
Conversion (in shares)	43,600
PU
Non-option activity (in shares)
Conversion (in shares)	138,800
Biogen | MSU
Non-option activity (weighted average)
Average closing stock price period			30 days	30 days
Assumptions
Expected dividend yield			0.00%	0.00%
Expected stock price volatility, minimum (as a percent)			38.20%	31.00%
Expected stock price volatility, maximum (as a percent)			40.70%	33.20%
Risk-free interest rate, minimum (as a percent)			0.60%	0.20%
Risk-free interest rate, maximum (as a percent)			0.90%	1.00%
30 calendar day average stock price on grant date, minimum			$ 260.67	$ 277.35
30 calendar day average stock price on grant date, maximum			304.86	426.27
Fair value (in dollars per share)			$ 326.65	$ 499.25
Sanofi | RSUs
Non-option activity (weighted average)
Purchase price (in dollars per share)					$ 105

Related Parties (Details)

Related Parties (Details) - USD ($) $ in Millions	Feb. 01, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related parties
Due to Biogen		$ 90.5
Biogen
Related parties
Net sales to Biogen		668.8
Due to Biogen		90.5
Total corporate overhead and other allocations from Biogen		11.8	$ 150	$ 148.6
Research and development | Biogen
Related parties
Total corporate overhead and other allocations from Biogen		6.5	88.7	84.5
Selling, general and administrative | Biogen
Related parties
Total corporate overhead and other allocations from Biogen		5.1	60.7	64
Other (income) expense, net allocations | Biogen
Related parties
Total corporate overhead and other allocations from Biogen		$ 0.2	$ 0.6	$ 0.1
Maximum | Biogen
Related parties
Agreement term	2 years

Other Consolidated Financial 68

Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accrued expenses and other
Revenue-related rebates	$ 47.9	$ 21.7
Employee compensation and benefits	52.4	15.9
Research and development	9.9	5.5
Royalty and collaboration	38.8	26.6
Short-term portion of contingent consideration	49.2
Taxes payable	9.4	10.8
Other	25.9	8.8
Total accrued expenses and other current liabilities	233.5	89.3
Other Long-Term Liabilities
Employee compensation and benefits		18.7
Sobi payments	87.8	45
Other	4.7
Total long term liabilities	$ 92.5	$ 63.7

Commitments and Contingencies69

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jun. 28, 2017	Jan. 31, 2014
Loss Contingencies [Line Items]
Potential future milestone payments	$ 755
Lease rental expense	6.8
Minimum rental commitments
2,018	6.6
2,019	6.7
2,020	6.1
2,021	6
2,022	6.1
Thereafter	24.9
Total	$ 56.4
True North
Loss Contingencies [Line Items]
Potential future milestone payments		$ 425
Sangamo
Loss Contingencies [Line Items]
Potential future milestone payments			$ 215

Guarantees (Details)

Guarantees (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Guarantees
Guarantee liability	$ 0	$ 0

Segment Information (Product) (

Segment Information (Product) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment									1
Product, net	$ 308.4	$ 274.8	$ 263.9	$ 242	$ 241.8	$ 217.1	$ 204.9	$ 182.8	$ 1,089.1	$ 846.6	$ 554.1
ELOCTATE
Segment Reporting Information [Line Items]
Product, net									724.5	513	319.7
ALPROLIX
Segment Reporting Information [Line Items]
Product, net									364.6	333.6	234.4
United States
Segment Reporting Information [Line Items]
Product, net									905.7	713.2	517.1
United States | ELOCTATE
Segment Reporting Information [Line Items]
Product, net									615.6	445.3	308.3
United States | ALPROLIX
Segment Reporting Information [Line Items]
Product, net									290.1	267.9	208.8
All Other Markets
Segment Reporting Information [Line Items]
Product, net									183.4	133.4	37
All Other Markets | ELOCTATE
Segment Reporting Information [Line Items]
Product, net									108.9	67.7	11.4
All Other Markets | ALPROLIX
Segment Reporting Information [Line Items]
Product, net									$ 74.5	$ 65.7	$ 25.6

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Product, net	$ 308.4	$ 274.8	$ 263.9	$ 242	$ 241.8	$ 217.1	$ 204.9	$ 182.8	$ 1,089.1	$ 846.6	$ 554.1
Revenue from collaborative partners	20.3	$ 16.8	$ 25.2	$ 17.1	14.4	$ 12.1	$ 5.4	$ 8.9	79.4	40.8	6.2
Long-lived assets	24				28.4				24	28.4	75.5
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Product, net									905.7	713.2	517.1
Revenue from collaborative partners									79.4	40.8	6.2
Long-lived assets	22.9				27.7				22.9	27.7	75
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Product, net									138.8	105.7	37
Long-lived assets	0.8				$ 0.7				0.8	0.7	$ 0.5
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Product, net									44.6	$ 27.7
Long-lived assets	$ 0.3								$ 0.3

Quarterly Financial Data (Una73

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data (Unaudited)
Product, net	$ 308.4	$ 274.8	$ 263.9	$ 242	$ 241.8	$ 217.1	$ 204.9	$ 182.8	$ 1,089.1	$ 846.6	$ 554.1
Collaboration	20.3	16.8	25.2	17.1	14.4	12.1	5.4	8.9	79.4	40.8	6.2
Total revenues	328.7	291.6	289.1	259.1	256.2	229.2	210.3	191.7	1,168.5	887.4	560.3
Gross profit	258.4	226.1	208.6	195.8	180.5	157.7	152.1	159.2	888.9	649.5
Net income	$ 141.3	$ 67.9	$ 77.1	$ 69.3	$ 228.9	$ 80.5	$ 63.5	$ 66.7	$ 355.6	$ 439.6	$ 108.6

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 21, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Subsequent Event | Sanofi | Bioverativ
Subsequent Event
Purchase price (in dollars per share)	$ 105
Potential termination fee payable	$ 326
Superior proposal for the outstanding equity interests (as a percent)	50.00%
Superior proposal for the assets (as a percent)	50.00%