COLLABORATIONS AND OTHER ARRANGEMENTS	3 Months Ended
COLLABORATIONS AND OTHER ARRANGEMENTS	Mar. 31, 2021
Collaborative and Other Arrangements [Abstract]
COLLABORATIONS AND OTHER ARRANGEMENTS	COLLABORATIONS AND OTHER ARRANGEMENTS We continue to pursue licensing and strategic collaborations and other similar arrangements with third parties for the development and commercialization of certain products and product candidates. These arrangements may involve two or more parties who are active participants in the operating activities of the collaboration and are exposed to significant risks and rewards depending on the commercial success of the activities. These arrangements may include non-refundable upfront payments, expense reimbursements or payments by us for options to acquire certain rights, contingent obligations by us for potential development and regulatory milestone payments and/or sales-based milestone payments, royalty payments, revenue or profit-sharing arrangements and cost-sharing arrangements. We also continue to pursue equity investments in third parties focused on the development and commercialization of products and product candidates. Merck Sharp & Dohme Corp. (“Merck”) On March 13, 2021, we entered into a license and collaboration agreement with Merck, a subsidiary of Merck & Co., Inc. to jointly develop and commercialize long-acting investigational treatments in HIV that combine Gilead’s investigational capsid inhibitor, lenacapavir, and Merck’s investigational nucleoside reverse transcriptase translocation inhibitor, islatravir. The collaboration will initially focus on long-acting oral and injectable formulations. Under the terms of the agreement, Gilead and Merck will share global development and commercialization costs at 60% and 40%, respectively, across the oral and injectable formulation programs. For long-acting oral products, Gilead will lead commercialization in the U.S. and Merck will lead commercialization in the European Union (“EU”) and rest of the world. For long-acting injectable products, Merck will lead commercialization in the U.S. and Gilead will lead commercialization in the EU and rest of the world. Gilead and Merck will jointly promote the combination products in the U.S. and certain other major markets. We will share global product revenues with Merck equally until product revenues surpass certain pre-determined per formulation revenue tiers. Upon passing $2.0 billion in net product sales for the oral combination in a given calendar year, our share of revenue will increase to 65% for any revenues above the threshold for such calendar year. Upon passing $3.5 billion in net product sales for the injectable combination in a given calendar year, our share of revenue will increase to 65% for any revenues above the threshold for such calendar year. There was no material impact from the agreement on our Condensed Consolidated Financial Statements for the three months ended March 31, 2021. We will also have the option to license certain of Merck’s investigational oral integrase inhibitors to develop in combination with lenacapavir. Reciprocally, Merck will have the option to license certain of Gilead’s investigational oral integrase inhibitors to develop in combination with islatravir. Each company may exercise its option for such investigational oral integrase inhibitor of the other company within the first five years after execution of the agreement, following completion of the first Phase 1 clinical trial of that integrase inhibitor. Upon exercise of an option, the companies will split development cost and revenues, unless the non-exercising company decides to opt-out, in which case the non-exercising company will be paid a royalty. Arcus Biosciences, Inc. (“Arcus”) On May 27, 2020, we entered into a transaction with Arcus, which included entry into an option, license and collaboration agreement (the “Collaboration Agreement”) and a common stock purchase agreement and an investor rights agreement (together, and as subsequently amended the “Stock Purchase Agreements”). In 2020, pursuant to the Stock Purchase Agreements and a separate secondary equity offering, we acquired approximately 8.2 million shares of Arcus common stock for approximately $261 million. In the first quarter of 2021, we amended and restated the common stock purchase agreement and acquired approximately 5.7 million additional shares of Arcus common stock for $220 million. As a result, we currently own a total of 13.8 million shares of Arcus, which represented approximately 19.5% of the issued and outstanding voting stock of Arcus immediately following the closing of the transaction. We recorded our equity investments in Arcus in Other long-term assets on our Condensed Consolidated Balance Sheets as the investments are subject to contractual lock-up provisions, subject to certain conditions. We account for our equity investments in Arcus at fair value with changes in fair value recognized in Other income (expense), net on our Condensed Consolidated Statements of Income for each reporting period. Under the Stock Purchase Agreements, we have the right to purchase additional shares of Arcus from Arcus over the five year period beginning on the closing of the Stock Purchase Agreements, up to a maximum of 35% of the outstanding voting stock. We are subject to a three year standstill, which period began on the date the parties entered into the Stock Purchase Agreements, restricting our ability to acquire voting stock of Arcus exceeding more than 35% of the then issued and outstanding voting stock of Arcus, subject to certain exceptions. Additionally, we agreed not to dispose of any equity securities of Arcus prior to the second anniversary of the closing of the Stock Purchase Agreements without the prior consent of Arcus, subject to certain exceptions. The amendment and restatement of the common stock purchase agreement in the first quarter of 2021 did not modify any of these terms. Other Arrangements During the three months ended March 31, 2021 and 2020, we entered into several collaborations, equity investments and licensing arrangements as well as other similar arrangements that we do not consider to be individually material. We recorded upfront collaboration expenses related to these arrangements of $62 million and $97 million for the three months ended March 31, 2021 and 2020, respectively, within Acquired in-process research and development expenses on our Condensed Consolidated Statements of Income. Cash payments made related to our equity investments were $59 million and $8 million for the three months ended March 31, 2021 and 2020, respectively, which were primarily recorded in Other long-term assets on our Condensed Consolidated Balance Sheets. Under the financial terms of these arrangements, we may be required to make payments upon achievement of developmental, regulatory and commercial milestones, which could be significant. Future milestone payments, if any, will be reflected in our Condensed Consolidated Statements of Income when the corresponding events become probable. In addition, we may be required to pay significant royalties on future sales if products related to these arrangements are commercialized. The payment of these amounts, however, is contingent upon the occurrence of various future events, which have a high degree of uncertainty of occurrence.