1. Summary of significant accounting policies

Basis of presentation

The accompanying unaudited condensed consolidated financial statements reflect the accounts of Seattle Genetics, Inc. and its wholly-owned subsidiaries (collectively “Seattle Genetics” or the “Company”). All intercompany transactions and balances have been eliminated. Management has determined that the Company operates in one segment: the development and sale of pharmaceutical products on its own behalf or in collaboration with others. Substantially all of the Company’s assets and revenues are related to operations in the United States; however, the Company also has subsidiaries in Canada, Switzerland and the United Kingdom.

The condensed consolidated balance sheet data as of December 31, 2016 were derived from audited financial statements not included in this quarterly report on Form 10-Q. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission, or SEC, and generally accepted accounting principles in the United States of America, or GAAP, for unaudited condensed consolidated financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The accompanying unaudited condensed consolidated financial statements reflect all adjustments consisting of normal recurring adjustments which, in the opinion of management, are necessary for a fair statement of the Company’s financial position and results of its operations, as of and for the periods presented.

Unless indicated otherwise, all amounts presented in financial tables are presented in thousands, except for per share and par value amounts.

These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016, as filed with the SEC.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The results of the Company’s operations for the three and nine month periods ended September 30, 2017 are not necessarily indicative of the results to be expected for the full year.

Non-cash investing activities

The Company had $1.2 million and $8.1 million of accrued capital expenditures as of September 30, 2017 and December 31, 2016, respectively. Accrued capital expenditures have been treated as a non-cash investing activity and, accordingly, have not been included in the statement of cash flows until such amounts have been paid in cash.

Investments

The Company invests cash resources primarily in debt securities. In addition, as of September 30, 2017, the Company held an equity investment in the common stock of Immunomedics, Inc., or Immunomedics, as further described in Note 7. These debt and equity securities are classified as available-for-sale, which are reported at estimated fair value with unrealized gains and losses included in accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains, realized losses and declines in the value of securities judged to be other-than-temporary, are included in investment and other income, net. The cost of investments for purposes of computing realized and unrealized gains and losses is based on the specific identification method. Amortization of premiums and accretion of discounts on debt securities are included in investment and other income, net. Interest and dividends earned on all securities are included in investment and other income, net. The Company classifies investments in debt securities maturing within one year of the reporting date, or where management’s intent is to use the investments to fund current operations or to make them available for current operations, as short-term investments. The Company classifies its equity investment in Immunomedics in other non-current assets.

If the estimated fair value of a security is below its carrying value, the Company evaluates whether it is more likely than not that it will sell the security before its anticipated recovery in market value and whether evidence indicating that the cost of the investment is recoverable within a reasonable period of time outweighs evidence to the contrary. The Company also evaluates whether or not it intends to sell the investment. If the impairment is considered to be other-than-temporary, the security is written down to its estimated fair value. In addition, the Company considers whether credit losses exist for any securities. A credit loss exists if the present value of cash flows expected to be collected is less than the amortized cost basis of the security. Other-than-temporary declines in estimated fair value and credit losses are charged against investment and other income, net.

Derivative financial instruments

The Company holds a warrant to purchase 8.7 million shares of Immunomedics common stock, which is accounted for as a derivative. The Company does not hold derivative instruments for trading or speculative purposes. The Company accounts for financial instruments as derivatives when the instrument includes an underlying and notional amount or payment provision, an initial net investment, and a net settlement. Derivative financial instruments are measured at fair value on the issuance date and are revalued on each subsequent balance sheet date. The Company uses the Black-Scholes model using observable market inputs to estimate the fair value of derivatives. The changes in estimated fair value are recognized as current period income or loss.

Other non-current assets

Other non-current assets included a $5.0 million non-controlling investment in a privately-held company that is accounted for under the cost method of accounting. The Company periodically evaluates the carrying value of the investment if significant adverse events or circumstances indicate an impairment in value. As of September 30, 2017, no impairment in value had been observed.

Long-term incentive plans

The Company has established Long-Term Incentive Plans, or LTIPs. The LTIPs provide eligible employees with the opportunity to receive performance-based incentives, which may be comprised of a cash payment, stock options, and/or restricted stock units. As of September 30, 2017, the estimated unrecognized compensation expense related to the LTIPs was $36.0 million. The total estimate of unrecognized compensation expense is expected to change in the future for several reasons, including the addition of more eligible employees, or the addition, termination, or modification of an LTIP.

Revenue recognition

The Company’s revenues are comprised of ADCETRIS^® net product sales, amounts earned under its collaboration and licensing agreements and royalties. Revenue recognition is predicated upon persuasive evidence of an agreement existing, delivery of products or services being rendered, amounts payable being fixed or determinable, and collectibility being reasonably assured.

Net product sales

The Company sells ADCETRIS through a limited number of pharmaceutical distributors in the U.S. and Canada. Customers order ADCETRIS through these distributors and the Company typically ships product directly to the customer. The Company records product sales when title and risk of loss pass, which generally occurs upon delivery of the product to the customer. Product sales are recorded net of estimated government-mandated rebates and chargebacks, distribution fees, estimated product returns and other deductions. Accruals are established for these deductions and actual amounts incurred are offset against applicable accruals. The Company reflects these accruals as either a reduction in the related account receivable from the distributor, or as an accrued liability depending on the nature of the sales deduction. Sales deductions are based on management’s estimates that consider payer mix in target markets and experience to date. These estimates involve a substantial degree of judgment.

Government-mandated rebates and chargebacks: The Company has entered into a Medicaid Drug Rebate Agreement, or MDRA, with the Centers for Medicare & Medicaid Services. This agreement provides for a rebate based on covered purchases of ADCETRIS. Medicaid rebates are invoiced to the Company by the various state Medicaid programs. The Company estimates Medicaid rebates based on a variety of factors, including its experience to date. The Company has also completed a Federal Supply Schedule, or FSS, agreement under which certain U.S. government purchasers receive a discount on eligible purchases of ADCETRIS. The Company has entered into a Pharmaceutical Pricing Agreement with the Secretary of Health and Human Services, which enables certain entities that qualify for government pricing under the Public Health Services Act, or PHS, to receive discounts on their qualified purchases of ADCETRIS. Under these agreements, distributors process a chargeback to the Company for the difference between wholesale acquisition cost and the applicable discounted price. As a result of the Company’s direct-ship distribution model, it can determine the entities purchasing ADCETRIS and this information enables the Company to estimate expected chargebacks for FSS and PHS purchases based on each entity’s eligibility for the FSS and PHS programs. The Company also reviews historical rebate and chargeback information to further refine these estimates.

Distribution fees, product returns and other deductions: The Company’s distributors charge a volume-based fee for distribution services that they perform for the Company. The Company allows for the return of product that is within 30 days of its expiration date or that is damaged. The Company estimates product returns based on its experience to date. In addition, the Company considers its direct-ship distribution model, its belief that product is not typically held in the distribution channel, and the expected rapid use of the product by healthcare providers. The Company provides financial assistance to qualifying patients that are underinsured or cannot cover the cost of commercial coinsurance amounts through SeaGen Secure. SeaGen Secure is available to patients in the U.S. and its territories who meet various financial and treatment need criteria. Estimated contributions for commercial coinsurance under SeaGen Secure are deducted from gross sales and are based on an analysis of expected plan utilization. These estimates are adjusted as necessary to reflect the Company’s actual experience.

Collaboration and license agreement revenues

The Company has developed a proprietary technology for linking cytotoxic agents to monoclonal antibodies called antibody-drug conjugates, or ADCs. This proprietary technology is the basis of ADC collaborations that the Company has entered into in the ordinary course of its business with a number of biotechnology and pharmaceutical companies. Under these ADC collaboration agreements, the Company grants its collaborators research and commercial licenses to the Company’s technology and provides technology transfer services, technical advice, supplies and services for a period of time.

If there are continuing performance obligations, the Company uses a time-based proportional performance model to recognize revenue over the Company’s performance period for the related agreement. Collaboration and license agreements are evaluated to determine whether the multiple elements and associated deliverables can be considered separate units of accounting. To date, the pre-commercial deliverables under the Company’s collaboration and license agreements have not qualified as separate units of accounting. The assessment of multiple element arrangements requires judgment in order to determine the appropriate point in time, or period of time, that revenue should be recognized. The Company believes that the development period in each agreement is a reasonable estimate of the performance obligation period of such agreement. Accordingly, all amounts received or due, including any upfront payments, maintenance fees, development and regulatory milestone payments and reimbursement payments, are recognized as revenue over the performance obligation periods of each agreement. These performance obligation periods typically range from one to three years. The agreements with Takeda Pharmaceutical Company Limited, or Takeda, and Genentech, Inc., a member of the Roche Group, or Genentech, have performance obligation periods of ten and seventeen years, respectively. All of the remaining performance obligation periods for active collaborations are currently expected to be completed in three years or less. When no performance obligations are required of the Company, or following the completion of the performance obligation period, such amounts are recognized as revenue when collectibility is reasonably assured. Generally, all amounts received or due other than sales-based milestones and royalties are classified as collaboration and license agreement revenues as they are earned. Sales-based milestones and royalties are recognized as royalty revenue as they are reported to the Company.

The Company’s collaboration and license agreements include contractual milestones. Generally, the milestone events contained in the Company’s collaboration and license agreements coincide with the progression of the collaborators’ product candidates from development, to regulatory approval and then to commercialization and fall into the following categories.

Development milestones in the Company’s collaborations may include the following types of events:

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Designation of a product candidate or initiation of preclinical studies. The Company’s collaborators must undertake significant preclinical research and studies to make a determination of the suitability of a product candidate and the time from those studies or designation to initiation of a clinical trial may take several years.

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Initiation of a phase 1 clinical trial. Generally, phase 1 clinical trials may take one to two years to complete.

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Initiation of a phase 2 clinical trial. Generally, phase 2 clinical trials may take one to three years to complete.

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Initiation of a phase 3 clinical trial. Generally, phase 3 clinical trials may take two to six years to complete.

Regulatory milestones in the Company’s collaborations may include the following types of events:

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Filing of regulatory applications for marketing approval such as a Biologics License Application in the United States or a Marketing Authorization Application in Europe. Generally, it may take up to twelve months to prepare and submit regulatory filings.

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Receiving marketing approval in a major market, such as in the United States, Europe, Japan or other significant countries. Generally, it may take up to three years after a marketing application is submitted to obtain approval for marketing and pricing from the applicable regulatory agency.

Commercialization milestones in the Company’s collaborations may include the following types of events:

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First commercial sale in a particular market, such as in the United States, Europe, Japan or other significant countries.

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Product sales in excess of a pre-specified threshold. The amount of time to achieve this type of milestone depends on several factors, including, but not limited to, the dollar amount of the threshold, the pricing of the product, market penetration of the product and the rate at which customers begin using the product.

The Company’s ADC collaborators are solely responsible for the development of their product candidates and the achievement of milestones in any of the categories identified above is based solely on the collaborators’ efforts.

In the case of the Company’s ADCETRIS collaboration with Takeda, the Company may be involved in certain development activities; however, the achievement of milestone events under the agreement is primarily based on activities undertaken by Takeda.

The process of successfully developing a product candidate, obtaining regulatory approval and ultimately commercializing a product candidate is highly uncertain and the attainment of any milestones is therefore uncertain and difficult to predict. In addition, since the Company does not take a substantive role or control the research, development or commercialization of any products generated by its ADC collaborators, the Company is not able to reasonably estimate when, if at all, any milestone payments or royalties may be payable to the Company by its ADC collaborators. As such, the milestone payments associated with its ADC collaborations involve a substantial degree of uncertainty and risk that they may never be received. Similarly, even in those collaborations where the Company may have an active role in the development of the product candidate, such as the Company’s ADCETRIS collaboration with Takeda, the attainment of a milestone is based on the collaborator’s activities and is generally outside the direction and control of the Company.

The Company generally invoices its collaborators and licensees on a monthly or quarterly basis, or upon the completion of the effort or achievement of a milestone, based on the terms of each agreement. Deferred revenue arises from amounts received in advance of the culmination of the earnings process and is recognized as revenue in future periods when the applicable revenue recognition criteria have been met. Deferred revenue expected to be recognized within the next twelve months is classified as a current liability.

Royalty revenues and cost of royalty revenues

Royalty revenues primarily reflect amounts earned under the ADCETRIS collaboration with Takeda. These royalties include sales royalties, which are based on a percentage of Takeda’s net sales at rates that range from the mid-teens to the mid-twenties based on sales volume, and commercial sales-based milestones. Takeda bears a portion of third-party royalty costs owed on its sales of ADCETRIS. This amount is included in royalty revenue in the Company’s consolidated financial statements. Cost of royalty revenues reflects amounts owed to the Company’s third-party licensors related to Takeda’s sales of ADCETRIS. These amounts are recognized in the quarter in which Takeda reports its sales activity to the Company, which is the quarter following the related sales. Royalty revenues also include amounts earned in connection with the Company’s ADC collaborations.

Recent accounting pronouncements

In May 2014, the Financial Accounting Standards Board, or FASB, issued an Accounting Standards Update entitled “ASU 2014-09, Revenue from Contracts with Customers.” The standard requires entities to recognize revenue through an evaluation that includes identification of the contract, identification of the performance obligations, determination of the transaction price, allocation of the transaction price to the performance obligations, and recognition of revenue as the entity satisfies the performance obligations. In August 2015, FASB issued an Accounting Standards Update entitled “ASU 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date”, which defers the effective date of ASU 2014-09 to the Company’s fiscal year beginning January 1, 2018. The FASB has continued to issue accounting standards updates to clarify and provide implementation guidance related to Revenue from Contracts with Customers, including “ASU 2016-08, Revenue from Contract with Customers: Principal versus Agent Considerations”, “ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing”, “ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients” and “ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers.” The Company’s preliminary assessment of this new standard is that it will generally not change the way in which the Company recognizes product revenue from sales of ADCETRIS. However, the Company expects that sales-based royalties and commercial sales-based milestones will be recorded in the period of the related sale based on estimates, rather than recording them as reported by the customer. In addition, the Company expects that the achievement of development milestones under the Company’s collaborations will be recorded in the period their achievement becomes probable, which may result in their recognition earlier than under current accounting principles. The new standard also requires more extensive disclosures related to revenue recognition, particularly in quarterly financial statements. The Company will adopt the standard on January 1, 2018 and intends to use the modified retrospective method of adoption. The Company is continuing to evaluate the impact of the standard on all of its revenues, including those mentioned above, and its assessments may change in the future based on its ongoing evaluation.

In January 2016, FASB issued an Accounting Standards Update entitled “ASU 2016-01, Financial Instruments: Overall.” The standard addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. The Company will adopt the standard on January 1, 2018 using a modified retrospective approach. The standard will require that the Company record changes in the fair value of equity securities in net income or loss. The implementation of this standard is expected to increase the volatility of net income or loss to the extent that the Company continues to hold equity securities.

In February 2016, FASB issued an Accounting Standards Update entitled “ASU 2016-02, Leases.” The standard requires entities to recognize in the consolidated balance sheet a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term. The standard will become effective for the Company beginning January 1, 2019, with early adoption permitted. The Company is currently evaluating the guidance to determine the potential impact on its financial condition, results of operations and cash flows, and financial statement disclosures, and expects that the adoption of the standard will increase assets and liabilities related to the Company’s operating leases in the consolidated balance sheets.

In March 2016, FASB issued an Accounting Standard Update entitled “ASU 2016-09, Compensation – Stock Compensation.” The standard is intended to simplify certain elements of accounting for share-based payment transactions, including the income tax impact, classification of awards as either equity or liabilities, and classification on the statement of cash flows. In addition, the standard allows an entity-wide accounting policy election to either estimate the number of awards that are expected to vest, as currently required, or account for forfeitures when they occur. The Company has elected to continue estimating the number of awards that are expected to vest. The Company adopted the standard as of January 1, 2017. Since the Company has incurred annual net losses since its inception and maintains a full valuation allowance on its net deferred tax assets, the adoption did not have a material impact on the Company’s financial condition, results of operations and cash flows.

In October 2016, FASB issued an Accounting Standard Update entitled “ASU 2016-16, Accounting for Income Taxes: Intra-Entity Asset Transfers of Assets Other than Inventory.” The standard is intended to simplify the accounting for intercompany sales of assets other than inventory. Under current GAAP, the tax effects of intra-entity asset transfers are deferred until the transferred asset is sold to a third party or otherwise recovered through use. Under the new guidance, a reporting entity would recognize the tax expense from the sale of the asset in the seller’s jurisdiction when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. Any deferred tax asset that arises in the buyer’s jurisdiction would also be recognized at the time of the transfer. The standard will become effective for the Company beginning on January 1, 2018. The Company is currently evaluating the new standard; however, since the Company has incurred annual net losses since its inception and maintains a full valuation allowance on its net deferred tax assets, the adoption is not expected to have a material impact on the Company’s financial condition, results of operations and cash flows, or financial statement disclosures.

In June 2016, FASB issued an Accounting Standard Update entitled “ASU 2016-13, Financial Instruments: Credit Losses.” The objective of the standard is to provide information about expected credit losses on financial instruments at each reporting date, and to change how other than temporary impairments on investments securities are recorded. The standard will become effective for the Company beginning on January 1, 2020 with early adoption permitted. The Company is currently evaluating the guidance to determine the potential impact on its financial condition, results of operations and cash flows, and financial statement disclosures.

In January 2017, FASB issued an Accounting Standard Update entitled, “ASU 2017-01, Business Combinations: Clarifying the Definition of a Business.” The objective of the standard is to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions of assets or businesses. The Company adopted this standard on a prospective basis as of January 1, 2017. The adoption of this standard did not have a material impact on the Company’s financial condition, results of operations and cash flows, or financial statement disclosures.

In May 2017, FASB issued an Accounting Standard Update entitled, “ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting.” The objective of the standard is to provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The standard is applied prospectively to awards modified on or after the adoption date. The Company early adopted this standard on April 1, 2017. The adoption did not have a material impact on the Company’s financial condition, results of operations and cash flows.