Notes to Unaudited Condensed Financial Statements

Adaptive Biotechnologies Corporation (“we,” “us” or “our”) is a commercial-stage company advancing the field of immune-driven medicine by harnessing the inherent biology of the adaptive immune system to transform the diagnosis and treatment of disease. We believe the adaptive immune system is nature’s most finely tuned diagnostic and therapeutic for most diseases, but the inability to decode it has prevented the medical community from fully leveraging its capabilities. Our immune medicine platform is the foundation for our expanding suite of products and services. The cornerstone of our immune medicine platform and core immunosequencing product, immunoSEQ, serves as our underlying research and development engine and generates revenue from academic and biopharmaceutical customers. Our first clinical diagnostic product, clonoSEQ, is the first test authorized by the Food and Drug Administration (“FDA”) for the detection and monitoring of minimal residual disease (“MRD”) in patients with select blood cancers.

We were incorporated in the State of Washington on September 8, 2009 under the name Adaptive TCR Corporation. On December 21, 2011, we changed our name to Adaptive Biotechnologies Corporation. We are headquartered in Seattle, Washington.

Initial Public Offering

Our registration statement on Form S-1 related to our initial public offering (“IPO”) was declared effective on June 26, 2019, and our common stock began trading on the Nasdaq Global Select Market on June 27, 2019. On July 1, 2019, we completed our IPO in which we issued and sold 17,250,000 shares of common stock, including shares issued upon the exercise in full of the underwriters’ over-allotment option, at a public offering price of $20.00. We received approximately $316.0 million in net proceeds, after deducting underwriting discounts and commission of approximately $24.2 million and offering expenses of approximately $4.8 million.

Immediately prior to the completion of our IPO on July 1, 2019, 93,039,737 shares of convertible preferred stock then outstanding converted into an equivalent number of shares of common stock. On July 1, 2019, in connection with the closing of our IPO, our amended and restated articles of incorporation, as filed with the Secretary of State of the State of Washington, and our amended and restated bylaws became effective. Also on July 1, 2019, we adopted a new equity incentive plan (“2019 Plan”), establishing an initial reserve of 15,519,170 shares under the 2019 Plan.

The condensed financial statements as of June 30, 2019, including share and per share amounts, do not give effect to our IPO as it closed subsequent to June 30, 2019.

Basis of Presentation and Use of Estimates

The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenues and expenses during the periods presented. We base our estimates on historical experience and other relevant assumptions that we believe to be reasonable under the circumstances. Estimates are used in several areas including, but not limited to, estimates of progress to date for certain performance obligations and the transaction price for certain contracts with customers, share-based compensation including the fair value of stock, and the provision for income taxes, including related reserves, and goodwill, among others. These estimates generally involve complex issues and require judgments, involve the analysis of historical results and prediction of future trends, can require extended periods of time to resolve and are subject to change from period to period. Actual results may differ materially from management’s estimates.

Unaudited Interim Condensed Financial Statements

In our opinion, the accompanying unaudited condensed financial statements have been prepared in accordance with GAAP for interim financial information. These unaudited condensed financial statements include all adjustments necessary to fairly state the financial position and the results of our operations and cash flows for interim periods in accordance with GAAP. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period.

The accompanying condensed financial statements should be read in conjunction with our audited financial statements and notes included in our prospectus dated June 26, 2019 filed with the Securities and Exchange Commission (“SEC”) on June 27, 2019 in connection with our IPO (“Prospectus”).

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Notes to Unaudited Condensed Financial Statements (Continued)

Cash and Cash Equivalents

Cash and cash equivalents are stated at fair value. Cash equivalents include only securities having an original maturity of three months or less at the time of purchase. We limit our credit risk associated with cash and cash equivalents by placing our investments with banks that we believe are highly creditworthy and with highly rated money market funds. Cash and cash equivalents primarily consist of bank deposits and investments in money market funds, as well as highly liquid U.S. government debt and agency securities and commercial paper with original maturities of three months or less.

Concentrations of Risk

We are subject to a concentration of risk from a limited number of suppliers, or in some cases, single suppliers for some of our laboratory instruments and materials. This risk is managed by targeting a quantity of surplus stock.

Cash, cash equivalents and marketable securities are financial instruments that potentially subject us to concentrations of credit risk. We invest in money market funds, U.S. government debt securities, U.S. government agency bonds, commercial paper and corporate bonds with high-quality accredited financial institutions.

Significant customers are those which represent more than 10% of our total revenue or accounts receivable balance at each respective balance sheet date. Revenue from these customers reflects their purchase of our products and services and we do not believe their loss would have a material adverse effect on our business.

For each significant customer, revenue as a percentage of total revenue and accounts receivable, net as a percentage of total accounts receivable, net were as follows:

Revenue Recognition

We recognize revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606 (“ASC 606”), Revenue from Contracts with Customers. Under ASC 606, for all revenue-generating contracts, we perform the following steps to determine the amount of revenue to be recognized: (i) identify the contract or contracts; (ii) determine whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measure the transaction price, including the constraint on variable consideration; (iv) allocate the transaction price to the performance obligations based on estimated selling prices; and (v) recognize revenue when (or as) we satisfy each performance obligation. The following is a summary of the application of the respective model to each of our revenue classifications.

Overview

Our revenue is generated from immunosequencing (“sequencing”) products and services (“sequencing revenue”) and from regulatory or development support services leveraging our immune medicine platform (“development revenue”). When revenue generating contracts have elements of both sequencing revenue and development revenue, we allocate revenue based on the nature of the performance obligation and the allocated transaction price.

Sequencing Revenue

Sequencing revenue reflects the amounts generated from providing sequencing services and testing through our immunoSEQ and clonoSEQ products and services to our research and clinical customers, respectively.

For research customers, contracts typically include an amount billed in advance of services (“upfront”), and subsequent billings as sample results are delivered to the customer. Upfront amounts received are recorded as deferred revenue, which we recognize as revenue upon satisfaction of performance obligations. We have identified two typical performance obligations under the terms of our

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Notes to Unaudited Condensed Financial Statements (Continued)

research service contracts: sequencing services and related data analysis. We recognize revenue for both identified performance obligations as sample results are delivered to the customer.

For other research customers who choose to purchase a research use only kit, the kits are sold on a price per kit basis with amounts payable upon delivery of the kit. Payments received are recorded as deferred revenue. For these customers, we have identified one performance obligation: the delivery of sample results. We recognize revenue as the results are delivered to the customer based on a proportion of the estimated samples that can be reported on for each kit.

For clinical customers, we derive revenues from providing our clonoSEQ test report to ordering physicians, and we bill and receive payments from commercial third-party payors and medical institutions. In these transactions, we have identified one performance obligation: the delivery of a clonoSEQ report. As payment from the respective payors may vary based on the various reimbursement rates and patient responsibilities, we consider the transaction price to be variable and record an estimate of the transaction price, subject to the constraint for variable consideration, as revenue at the time of delivery. The estimate of transaction price is based on historical reimbursement rates with the various payors, which are monitored in subsequent periods and adjusted as necessary based on actual collection experience.

In January 2019, clonoSEQ received Medicare coverage aligned with the FDA label and National Comprehensive Cancer Network (“NCCN”) guidelines for longitudinal monitoring in multiple myeloma (“MM”) and B cell acute lymphoblastic leukemia (“ALL”). We bill Medicare for an episode of treatment when we deliver the first eligible test results. This billing contemplates all necessary tests required during a patient’s treatment cycle, which is currently estimated at approximately four tests per patient, including the initial sequence identification test. Revenue is recognized at the time the initial billable test result is delivered and is based upon cumulative tests delivered to date. For the three and six months ended June 30, 2019, we recognized $0.3 million and $0.8 million relating to the coverage policy, respectively; $0.1 million and $0.4 million of this revenue was related to tests delivered in periods prior to the three and six months ended June 30, 2019, respectively. Any unrecognized revenue from the initial billable test is recorded as deferred revenue, and is recognized as we deliver the remaining tests in a patient’s treatment cycle.

Development Revenue

We derive revenue by providing services through development agreements to biopharmaceutical customers who seek access to our immune medicine platform technologies. We generate revenues from the delivery of professional support activities pertaining to the use of our proprietary immunoSEQ and clonoSEQ services in the development of the respective customers’ initiatives. The transaction price for these contracts may consist of a combination of non-refundable upfront fees, separately priced sequencing fees, progress based milestones and regulatory milestones. The development agreements may include single or multiple performance obligations depending on the contract. For certain contracts, we may perform services to support the biopharmaceutical customers’ regulatory submission as part of their registrational trials. These services include regulatory support pertaining to our technology intended to be utilized as part of the submission, development of analytical plans for our sequencing data, participation on joint research committees and assistance in completing a regulatory submission. Generally, these services are not distinct within the context of the contract, and they are accounted for as a single performance obligation.

When sequencing services are separately priced customer options, we assess if a material right exists and, if not, the customer option to purchase additional sequencing services is not considered part of the contract. Except for any non-refundable upfront fees, the other forms of compensation represent variable consideration. Variable consideration related to progress based and regulatory milestones is estimated using the most likely amount method where variable consideration is constrained until it is probable that a significant reversal of cumulative revenue recognized will not occur. Progress milestones such as the first sample result delivered or final patient enrollment in a customer trial are customer dependent and are included in the transaction price when the respective milestone is probable of occurring. Milestone payments that are not within our customers’ control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. Determining whether regulatory milestone payments are probable is an area that requires significant judgment. In making this assessment, we evaluate the scientific, clinical, regulatory and other risks that must be managed, as well as the level of effort and investment required to achieve the respective milestone.

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Notes to Unaudited Condensed Financial Statements (Continued)

The primary method used to estimate standalone selling price for performance obligations is the adjusted market assessment approach. Using this approach, we evaluate the market in which we sell our services and estimate the price that a customer in that market would be willing to pay for our services. We recognize revenue using either an input or output measure of progress that faithfully depicts performance on a contract, depending on the contract. The measure used is dependent on the nature of the service to be provided in each contract. Selecting the measure of progress and estimating progress to date requires significant judgment.

Deferred Offering Costs

Deferred offering costs consist of fees and expenses incurred in connection with the anticipated sale of our common stock in the IPO, including the legal, accounting, printing and other IPO-related costs. Deferred offering costs of $4.8 million are capitalized and classified within restricted cash and other assets on the condensed balance sheet as of June 30, 2019.

Net Loss Per Share Attributable to Common Shareholders

We calculate our basic and diluted net loss per share attributable to common shareholders in conformity with the two-class method required for companies with participating securities. We consider our convertible preferred stock to be participating securities. In the event a dividend is declared or paid on common stock, holders of convertible preferred stock are entitled to a share of such dividend in proportion to the holders of common stock on an as-if converted basis. Under the two-class method, basic net loss per share attributable to common shareholders is calculated by dividing the net loss attributable to common shareholders by the weighted-average number of shares of common stock outstanding for the period. Net loss attributable to common shareholders is determined by allocating undistributed earnings between common and preferred shareholders. The diluted net loss per share attributable to common shareholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period determined using the treasury stock method. The net loss attributable to common shareholders was not allocated to the convertible preferred stock under the two-class method as the convertible preferred stock does not have a contractual obligation to share in our losses. For purposes of this calculation, convertible preferred stock, stock options and warrants to purchase common stock or convertible preferred stock are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common shareholders as their effect is anti-dilutive.

Recently Adopted Accounting Pronouncements

In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation—Stock Compensation (Topic 718), intended to simplify the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statements of cash flows. This guidance also allowed for an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures as they occur. We adopted this guidance as of January 1, 2018 and elected to account for forfeitures as they occur. We utilized a modified retrospective transition method, recorded the cumulative impact of applying this guidance, and recognized a cumulative increase to additional paid-in capital and an increase to accumulated deficit of $0.1 million.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, intended to simplify the goodwill impairment test. Under the new guidance, goodwill impairment is measured by the amount by which the carrying value of a reporting unit exceeds its fair value, without exceeding the carrying amount of goodwill allocated to that reporting unit. This guidance is effective January 1, 2022 and is required to be adopted on a prospective basis, with early adoption permitted. We adopted this guidance as of January 1, 2018 and the adoption did not have any impact on our financial statements.

In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, which expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The guidance is effective for us beginning in 2019, with early adoption permitted. We adopted the guidance effective January 1, 2019 and the adoption did not have any impact on our financial statements.

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New Accounting Pronouncements Not Yet Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), intended to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheets and disclosing key information about leasing arrangements. This guidance is effective for us in fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Although we are currently evaluating the impact that adopting this guidance will have on our financial statements, we believe the most significant changes will be related to the recognition of the right-of-use assets and related lease liabilities related to our operating leases on the balance sheets.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available-for-sale debt securities. The guidance is effective for us beginning in 2020, with early adoption permitted. Although we are currently evaluating the impact that adopting this guidance prospectively will have on our financial statements, we do not expect the adoption to have a material impact on our financial statements.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other: Internal-Use Software (Subtopic 350-40), to provide additional guidance on the accounting for costs of implementation activities performed in a cloud computing arrangement. This guidance is effective for fiscal years beginning after December 15, 2019 and early adoption of the amendments in this update are permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements.

Translational Development Agreements

On December 18, 2015, we entered into a translational development agreement with a biopharmaceutical customer for access to certain of our oncology immunosequencing research datasets, including full-time employee support, to accelerate the customer’s preclinical, nonclinical and clinical trial testing. Under the initial terms of the agreement we could be entitled to up to $40.0 million over a period of four years which does not include any separately negotiated research sequencing contracts. If the biopharmaceutical customer terminates the agreement prior to the end of the initial four-year research term for any reason other than a material uncured breach by us, then the biopharmaceutical partner has agreed to pay us $0.8 million. In May 2019, the agreement was subsequently amended to reduce the services provided, which in turn reduced the fourth year of eligible payments to $2.3 million.

We identified one performance obligation under this agreement, as the services were determined to be highly interrelated. We determined that any separately negotiated sequencing contracts are not performance obligations under the contract, as the contract did not contain any material rights related to such sequencing contracts. For the identified performance obligation, we assessed the work to be performed over the duration of the contract and determined that it is a consistent level of support throughout the period, and therefore revenue has been recognized straight-line over the contract term.

Revenue recognized from this translational development agreement, excluding separately negotiated research sequencing contracts, was $1.1 million and $2.5 million in the three months ended June 30, 2019 and 2018, respectively, and $1.1 million and $5.0 million in the six months ended June 30, 2019 and 2018, respectively.

In 2017, we entered into an agreement with a customer to provide services to accelerate its research initiatives. We identified one performance obligation under the agreement, as the services were determined to be highly interrelated. We determined that any separately negotiated sequencing contracts are not performance obligations under the contract, as the contract did not contain any material rights related to such sequencing contracts. Revenue recognized from this agreement, excluding sequencing revenue, was $0.1 million and $0.2 million in the three months ended June 30, 2019 and 2018, respectively, and $0.2 million and $0.3 million in the six months ended June 30, 2019 and 2018, respectively.

MRD Development Agreements

In 2017 and 2018, we entered into agreements with biopharmaceutical customers to further develop and commercialize clonoSEQ and the biopharmaceutical customers’ therapeutics. Under each of the agreements, we received or will receive non-refundable upfront payments and could receive substantial additional payments upon reaching certain progress milestones or achievement of certain regulatory milestones pertaining to the customers’ therapeutic and our clonoSEQ test.

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Under the contracts, we identify performance obligations, which may include: (i) obligations to provide services supporting the customer’s regulatory submission activities as they relate to our clonoSEQ test; and (ii) sequencing services for customer-provided samples for their regulatory submissions. The transaction price allocated to the respective performance obligations is estimated using an adjusted market assessment approach for the regulatory support services and a standalone selling price for the estimated immunosequencing services. At contract inception we fully constrained any consideration related to the regulatory milestones, as the achievement of such milestones is subject to third-party regulatory approval and the customers’ own submission decision-making. We recognize revenue relating to the sequencing services over time using an output method based on the proportion of sample results delivered relative to the total amount of sample results expected to be delivered and when expected to be a faithful depiction of progress. We use the same method to recognize the regulatory support services. When an output method based on the proportion of sample results delivered is not expected to be a faithful depiction of progress, we utilize an input method based on estimates of effort completed using a cost-based model.

We recognized $0.5 million and $0.6 million in development revenue related to these contracts in the three months ended June 30, 2019 and 2018, respectively, and $0.8 million and $1.9 million in the six months ended June 30, 2019 and 2018, respectively.

As of June 30, 2019, in future periods we could receive up to an additional $115.0 million in milestone payments if certain regulatory approvals are obtained by our customers’ therapeutics in connection with MRD data generated from our clonoSEQ test.

Genentech Collaboration Agreement

In December 2018, we entered into a worldwide collaboration and license agreement (“Genentech Agreement”) with Genentech, Inc. (“Genentech”) to leverage our capability to develop cellular therapies in oncology. Subsequent to receipt of regulatory approval in January 2019, we received a non-refundable upfront payment of $300.0 million in February 2019 and may be eligible to receive more than $1.8 billion over time, including payments of up to $75.0 million upon the achievement of specified regulatory milestones, up to $300.0 million upon the achievement of specified development milestones and up to $1,430.0 million upon the achievement of specified commercial milestones. In addition, we are separately able to receive tiered royalties at a rate ranging from the mid-single digits to the mid-teens on aggregate worldwide net sales of products arising from the strategic collaboration, subject to certain reductions, with aggregate minimum floors. Under the agreement, we are pursuing two product development pathways for novel T cell immunotherapies in which Genentech intends to use T cell receptors (“TCRs”) screened by our immune medicine platform to engineer and manufacture cellular medicines:

Under the terms of the agreement, we granted Genentech exclusive worldwide licenses to develop and commercialize TCR-based cellular therapies in the field of oncology, including licenses to existing shared antigen data packages. Additionally, Genentech has the right to determine which product candidates to further develop for commercialization purposes. We determined that this arrangement meets the criteria set forth in ASC Topic 808, Collaborative Arrangements (“ASC 808”), because both parties are active participants in the activity and are exposed to significant risks and rewards depending on the activity’s commercial failure or success. Because ASC 808 does not provide guidance on how to account for the activities under a collaborative arrangement, we applied the guidance in ASC 606 to account for the activities related to the Genentech collaboration.

In applying ASC 606, we identified the following performance obligations at the inception of the agreement:

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We determined that none of the licenses, research and development services or obligations to participate on various committees were distinct within the context of the contract given such rights and activities were highly interrelated and there was substantial additional research and development to further develop the licenses. We considered factors such as the stage of development of the respective existing antigen data packages, the subsequent development that would be required to both identify and submit a potential target for investigational new drug acceptance under both product pathways and the variability in research and development pathways given Genentech’s control of product commercialization. Specifically, under the agreement, Genentech is not required to pursue development or commercialization activities pertaining to both product pathways and may choose to proceed with one or the other as opposed to both. Accordingly, we determined that all of the identified performance obligations were attributable to one general performance obligation, which is to further the development of our TCR-specific platform, including data packages, and continue to make our TCR identification process available to Genentech to pursue either product pathway.

Separately, we have a responsibility to Genentech to enter into a supply and manufacturing agreement for patient specific TCRs as it pertains to any Personalized Product therapeutic. We determined this was an option right of Genentech should they pursue commercialization of a Personalized Product therapy. Because of the uncertainty as a result of the early stage of development, the novel approach of our collaboration with Genentech and our rights to future commercial milestones and royalty payments, we determined that this option right was not a material right that should be accounted for at inception. As such, we will account for the supply and manufacturing agreement when entered into between the parties.

We determined the initial transaction price shall be made up of only the $300.0 million upfront, non-refundable payment as all potential regulatory and development milestone payments were probable of significant revenue reversal as their achievement was highly dependent on factors outside our control. As a result, these payments were fully constrained and were not included in the transaction price as of June 30, 2019. We excluded the commercial milestones and potential royalties from the transaction price as those items relate predominantly to the license rights granted to Genentech and will be assessed when and if such events occur.

As there are potential substantive developments necessary, which Genentech may be able to direct, we determined that we would apply a proportional performance model to recognize revenue for our performance obligation. We measure proportional performance using an input method based on costs incurred relative to the total estimated costs of research and development efforts to pursue both the Shared Product and Personalized Product pathways. We currently expect to recognize the revenue over a period of approximately seven to eight years from the effective date. This estimate of the research and development period considers pursuit options of development activities supporting both the Shared Product and the Personalized Product, but may be reduced or increased based on the various activities as directed by the joint committees, decisions made by Genentech, regulatory feedback or other factors not currently known.

We recognized revenue of approximately $8.5 million and $14.8 million for the three and six months ended June 30, 2019, respectively, related to the Genentech collaboration. Costs related to the Genentech collaboration are included in research and development expenses.

The following table sets forth the fair value of financial assets and liabilities that were measured at fair value on a recurring basis (in thousands):

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Level 1 securities include highly liquid money market funds, which we measure the fair value based on quoted prices in active markets for identical assets or liabilities. Level 2 securities consist of U.S. government debt securities, U.S. government agency bonds, commercial paper and corporate bonds, and are valued based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data. Of the Level 2 commercial paper and U.S. government debt and agency securities balances, $6.0 million and $4.0 million, respectively, is recorded as cash and cash equivalents. Level 3 liabilities that are measured at fair value on a recurring basis consist of a convertible preferred stock warrant liability. During the six months ended June 30, 2019, we recognized $2.3 million of expense related to the revaluation of the convertible preferred stock warrant liability in interest and other income, net.

The fair value of the convertible preferred stock warrant liability is estimated using the Black-Scholes option-pricing model. Certain inputs were utilized in the option-pricing model as follows:

Available-for-sale investments consisted of the following as of June 30, 2019 and December 31, 2018 (in thousands):

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Notes to Unaudited Condensed Financial Statements (Continued)

The following table presents the gross unrealized holding losses and fair value for investments in an unrealized loss position, and the length of time that individual securities have been in a continuous loss position, as of June 30, 2019 (in thousands):