Document CONTACTS Investors Media Jacquie Ross Amy Flood (650) 574-3000 (650) 522-5643 For Immediate Release GILEAD SCIENCES ANNOUNCES FOURTH QUARTER AND FULL YEAR 2020 FINANCIAL RESULTS Fourth Quarter 2020 Year-Over-Yea

GILEAD SCIENCES ANNOUNCES FOURTH QUARTER AND FULL YEAR 2020 FINANCIAL RESULTS

Fourth Quarter 2020 Year-Over-Year

- Product Sales increased 26% to $7.3 billion, primarily due to Veklury (remdesivir) -

- Diluted EPS of $1.23 Non-GAAP Diluted EPS of $2.19 -

Full Year 2020 Year-Over-Year

- Product Sales increased 10% to $24.4 billion, primarily due to Veklury -

- Diluted EPS of $0.10 Non-GAAP Diluted EPS of $7.09 -

- Returned $5.0 billion of cash to shareholders through dividends and share repurchases -

Full Year 2021 Guidance

- Product Sales including Veklury of $23.7 billion to $25.1 billion -

- Operating expenses flat to low single-digit percentage decline -

- Non-GAAP Diluted EPS of $6.75 to $7.45 -

Foster City, CA, February 4, 2021 - Gilead Sciences, Inc. (Nasdaq GILD) announced today its results of operations for the fourth quarter and full year 2020.

"Gilead continues to play a central role in the pandemic, with Veklury now treating one in two hospitalized patients in the United States. At the same time, we continue to meet the needs of people living with HIV, cancer, viral hepatitis and other conditions," said Daniel O'Day, Chairman and Chief Executive Officer, Gilead Sciences. "As we head into 2021, we have many additional opportunities to help patients, especially in oncology where Trodelvy, for example has the potential to treat a broad range of cancer types. These new opportunities, together with our continued leadership in antivirals put Gilead on a clear path to growth."

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(1) Beginning in 2020, Gilead no longer regularly excludes share-based compensation expense from its non-GAAP financial information. To conform to this change, the prior period non-GAAP financial information has been recast to include share-based compensation expense. A reconciliation between GAAP and non-GAAP financial information is provided in the tables on pages 13 - 14.

Total revenues for the fourth quarter and full year 2020 increased 26% and 10%, respectively, compared to the same periods in 2019, primarily due to the launch of Veklury in 2020.

Product sales excluding Veklury sales for the fourth quarter and full year 2020 decreased 7% and 3%, respectively, compared to the same periods in 2019, due to the continued effects of COVID-19 on Gilead's HIV and hepatitis C virus ("HCV") franchises, as well as the expected decline in sales of Truvada (emtricitabine ("FTC") and tenofovir disoproxil fumarate ("TDF"))-based products due to the loss of exclusivity of Truvada and Atripla (efavirenz 600 mg emtricitabine 200 mg tenofovir disoproxil fumarate 300 mg) in the United States in October 2020. See further discussion below.

Veklury sales were $1.9 billion and $2.8 billion, for the fourth quarter and full year 2020, respectively, reflecting higher hospitalization and treatment rates due to the most recent COVID-19 surge.

Diluted EPS decreased 42% to $1.23 for the fourth quarter 2020, and 98% to $0.10 for the full year 2020, compared to the same periods in 2019, primarily due to changes in the fair value of Gilead's equity investments in Galapagos NV ("Galapagos"), a 2019 discrete tax benefit related to intra-entity transfers and higher acquisition-related expenses. Full year 2020 was also impacted by higher acquired in-process research and development ("IPR D") expenses.

Non-GAAP diluted EPS increased 99% to $2.19 for the fourth quarter 2020, and 16% to $7.09 for the full year 2020, compared to the same periods in 2019, primarily due to higher non-GAAP operating income driven by growth in product sales and improved gross margin, partially offset by higher research and development ("R D") investments and other operating expenses.

The following tables summarize significant items that affected the comparability of net income attributable to Gilead and diluted EPS for the periods presented

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(1) Represents charges recorded to write down slow moving and excess raw material and work in process inventory primarily in the fourth quarter 2019.

(2) Full year 2020 primarily reflects charges related to Gilead's acquisition of Forty Seven, Inc. ("Forty Seven") as well as collaborations and other investments Gilead entered into during the year. Fourth quarter 2019 includes a pre-tax $800 million impairment charge related to assets obtained in Gilead's Kite Pharma Inc. ("Kite") acquisition. Full year 2019 includes $3.9 billion in upfront charges related to Gilead's global research and development collaboration agreement with Galapagos.

(3) Primarily represents unrealized losses (gains) from changes in the fair value of Gilead's equity investments in Galapagos for the periods represented.

(4) Primarily represents accelerated stock-based compensation expenses recorded in Cost of goods sold, R D expenses and Selling, general and administrative ("SG A") expenses from the second quarter 2020 Forty Seven acquisition and the fourth quarter 2020 Immunomedics, Inc. ("Immunomedics") acquisition.

(5) Represents net favorable tax effects of intra-entity intangible asset transfers to different tax jurisdictions during the fourth quarter 2019.

(6) These amounts were excluded from non-GAAP net income and non-GAAP diluted EPS. A reconciliation between GAAP and non-GAAP financial information is provided in the tables on pages 13 - 14.

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(1) Trodelvy (sacituzumab govitecan-hziy 180 mg) sales for the fourth quarter and full year 2020, including the period prior to the completion of Gilead's acquisition of Immunomedics, were $64 million and $137 million, respectively.

Total product sales increased 26% to $7.3 billion for the fourth quarter 2020, and 10% to $24.4 billion for the full year 2020, respectively, compared to the same periods in 2019, primarily due to the launch of Veklury in 2020.

Product sales excluding Veklury sales decreased 7% and 3% for the fourth quarter and full year 2020, respectively, compared to the same periods in 2019, primarily due to the following

Lower HCV sales volume due to the impact of the COVID-19 pandemic as described below and

Expected decline in sales of Truvada-based products due to the loss of exclusivity of Truvada and Atripla in the United States in October 2020.

The decreases were partially offset by

Continued patient uptake of Biktarvy (bictegravir 50 mg emtricitabine 200 mg tenofovir alafenamide 25 mg) and

Growth of Descovy (emtricitabine 200 mg tenofovir alafenamide 25 mg) for pre-exposure prophylaxis ("PrEP") PrEP ("Descovy for PrEP").

The full year 2020 decrease was also due to the expected decline in sales of Letairis (ambrisentan 5 mg and 10 mg) and Ranexa (ranolazine 500 mg and 1000 mg) after generic entries in the first half of 2019.

Product sales for the fourth quarter 2020 were $5.3 billion in the United States, $1.4 billion in Europe and $656 million in other international locations. Product sales for the fourth quarter 2019 were $4.5 billion in the United States, $840 million in Europe and $440 million in other international locations. For 2020, product sales were $18.1 billion in the United States, $3.9 billion in Europe and $2.3 billion in other international locations. For 2019, product sales were $16.6 billion in the United States, $3.6 billion in Europe and $2.0 billion in other international locations.

HIV product sales decreased 7% to $4.3 billion for the fourth quarter 2020, and increased 3% to $16.9 billion for the full year 2020, compared to the same periods in 2019.

HIV product sales for the fourth quarter 2020 decreased primarily due to the following

Lower sales volume of Truvada (FTC TDF)-based products driven by the loss of exclusivity of Truvada and Atripla in the United States in October 2020, partially offset by the continued patient uptake of Biktarvy and growth of Descovy for PrEP and

Lower average net selling price driven by the effects of

Unfavorable payer mix primarily due to higher public health service utilization and

Product mix due to the loss of exclusivity of Truvada in the United States.

HIV products sales for the full year 2020 increased primarily due to the following

Continued patient uptake of Biktarvy and growth of Descovy for PrEP.

The increase was partially offset by

Lower sales volume of Truvada (FTC TDF)-based products driven by the loss of exclusivity of Truvada and Atripla in the United States in October 2020 and the COVID-19 pandemic impact on Gilead's HIV franchise and

Lower average net selling price driven by unfavorable payer mix primarily due to higher public health service utilization.

HCV product sales decreased 33% to $423 million for the fourth quarter 2020, and 30% to $2.1 billion for the full year 2020, compared to the same periods in 2019. The decreases were primarily due to the following

Lower sales volume driven by lower patient starts in the United States and Europe due to the COVID-19 pandemic and

Lower average net selling price reflecting higher sales return reserves and discounts.

Veklury sales contributed $1.9 billion and $2.8 billion in sales for the fourth quarter and full year 2020, respectively, primarily in the United States and Europe, with the fourth quarter volumes particularly reflecting higher hospitalization and treatment rates due to the most recent COVID-19 surge.

Cell therapy product sales, which include Yescarta (axicabtagene ciloleucel) and TecartusTM (brexucabtagene autoleucel), increased 34% to $163 million for the fourth quarter 2020, and 33% to $607 million for the full year 2020, compared to the same periods in 2019. The increases were primarily driven by the continued uptake of Yescarta in Europe and the third quarter 2020 product launch of Tecartus in the United States.

Trodelvy sales generated $49 million in sales in the United States, following the acquisition by Gilead of Immunomedics on October 23, 2020.

Other product sales, which include Vemlidy (tenofovir alafenamide 25 mg), Viread (tenofovir disoproxil fumarate 300 mg), Letairis, Ranexa, Zydelig (idelalisib 150 mg), AmBisome (amphotericin b liposome for injection 50 mg vial), Cayston (aztreonam for inhalation solution 75 mg vial) and Jyseleca (filgotinib), increased 7% to $498 million for the fourth quarter 2020, compared to the same period in 2019, primarily due to higher sales volume of Vemlidy in other international locations. Other product sales decreased 18% to $1.9 billion for the full year 2020, compared to the same period in 2019, primarily due to the expected declines in sales of Letairis and Ranexa after generic entries in the first half of 2019, partially offset by higher sales volume of Vemlidy in other international locations.

Cost of Goods Sold and Product Gross Margin

Cost of goods sold and non-GAAP cost of goods sold for the fourth quarter and full year 2020 decreased, compared to the same periods in 2019, primarily due to the $500 million charge recorded in the fourth quarter 2019 to write down inventory, which was driven by lower long-term demand for Gilead's HCV products.

The decrease for the full year 2020 was partially offset by higher manufacturing ramp-up expenses related to Veklury as a treatment for COVID-19. As previously disclosed, Gilead implemented process refinements and expanded its production capacity of Veklury to ensure the broader supply for patients during 2020.

Cost of goods sold for the fourth quarter 2020, compared to the same period in 2019, included higher acquisition-related expenses from amortization of intangible assets, inventory step-up charges and accelerated stock-based compensation expenses related to the Immunomedics acquisition.

Product Gross Margin

Product gross margin and non-GAAP product gross margin for the fourth quarter and full year 2020 improved year-over-year due to the fourth quarter 2019 inventory write-down described above.

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(1) Beginning in the second quarter 2020, Acquired IPR D expenses were reported separately from R D expenses in Gilead's Condensed Consolidated Statements of Income to provide additional information. The amounts for prior periods were reclassified to conform to the current period presentation. Acquired IPR D expenses have been historically excluded from Gilead's non-GAAP financial information.

R D expenses and non-GAAP R D expenses for the fourth quarter 2020 increased, compared to the same period in 2019, primarily due to the charge recorded in the fourth quarter 2020, in connection with the agreement to amend the existing arrangement with Galapagos for the commercialization and development of Jyseleca of $190 million ( 160 million), milestones of $70 million to Pionyr Immunotherapeutics, Inc. ("Pionyr"), and Trodelvy and other pipeline investments.

In addition to the drivers described above, R D expenses and non-GAAP R D expenses for the full year 2020 increased year-over-year primarily due to

Higher clinical trial expenses related to the investigation of remdesivir as a treatment for COVID-19 and higher investments in oncology programs, including magrolimab, an investigational anti-CD47 monoclonal antibody.

The increases were partially offset by lower clinical trial expenses from the completion of certain inflammation programs and lower costs as a result of Gilead's pause or postponement of certain clinical trials due to the COVID-19 pandemic.

R D expenses for the fourth quarter and full year 2020 also increased due to accelerated stock-based compensation expenses of $58 million and $166 million, respectively, related to the fourth quarter 2020 Immunomedics acquisition and, for the full year 2020, the second quarter 2020 Forty Seven acquisition.

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(1) Beginning in the second quarter 2020, Acquired IPR D expenses were reported separately from R D expenses in Gilead's Condensed Consolidated Statements of Income to provide additional information. The amounts for prior periods were reclassified to conform to the current period presentation. Acquired IPR D expenses have been historically excluded from Gilead's non-GAAP financial information.

Acquired IPR D expenses of $5.9 billion for the full year 2020 were primarily related to Gilead's acquisition of Forty Seven as well as collaborations and other investments Gilead entered into during the year, separately with Arcus Biosciences, Inc., Pionyr, Tango Therapeutics, Inc., Tizona Therapeutics, Inc. and Jounce Therapeutics, Inc.

Acquired IPR D expenses for the fourth quarter 2019 were related to the $800 million impairment charge from assets obtained in Gilead's Kite acquisition. Full year 2019 included $3.9 billion in upfront charges related to Gilead's global research and development collaboration agreement with Galapagos.

SG A expenses and non-GAAP SG A expenses for the fourth quarter 2020 increased, compared to the same period in 2019, primarily due to expenses related to additional funds allocated to corporate grants, including non-profit grantees to support racial equity and social justice efforts, the timing of marketing expenses related to Biktarvy, and commercialization efforts for Veklury and Trodelvy.

SG A expenses and non-GAAP SG A expenses for the full year 2020 increased year-over-year, primarily due to a $97 million charge related to a previously disclosed legal settlement, increased corporate grants, higher costs associated with the commercialization efforts for Veklury, marketing expenses related to Biktarvy and donations of remdesivir.

SG A expenses for the fourth quarter and full year 2020 also increased due to accelerated stock-based compensation expenses of $168 million and $204 million, respectively, related to the fourth quarter 2020 Immunomedics acquisition and, for the full year 2020, the second quarter 2020 Forty Seven acquisition.

The increases were partially offset by lower travel and other spend due to the COVID-19 pandemic.

Other Income (Expense), Net and Interest Expense

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The unrealized losses primarily relating to Gilead's investments in Galapagos unfavorably impacted Other income (expense), net for the fourth quarter and full year 2020, compared to unrealized gains in the prior year periods.

Interest expense for the fourth quarter 2020 increased primarily due to the senior unsecured notes issued in September 2020 and $1.0 billion borrowed under a three-year term loan facility related to the Immunomedics acquisition.

The effective tax rate ("ETR") and non-GAAP ETR for the fourth quarter 2020 were 14.9% and 15.8%, respectively, compared to (41.5)% and 31.5% for the same period in 2019. The year-over-year increase in ETR was primarily due to a $1.2 billion discrete tax benefit related to intra-entity intangible asset transfers to different tax jurisdictions recorded in the fourth quarter 2019. The year-over-year decrease in non-GAAP ETR was primarily due to a $114 million discrete tax expense related to the Altera Corp. v. Commissioner ruling recorded in the fourth quarter 2019. The ETR and non-GAAP ETR for the fourth quarter 2020 reflected $76 million of discrete tax benefits related to settlements with taxing authorities.

The ETR and non-GAAP ETR for the full year 2020 were 94.7% and 18.6%, respectively, compared to (4.0)% and 22.4% for the same period in 2019. The increase in ETR was primarily due to the above-mentioned unrealized losses on Gilead's equity investments in Galapagos and certain acquired IPR D charges in 2020 that were non-deductible for income tax purposes. In addition, the ETR for the full year 2019 included the $1.2 billion discrete tax benefit described above. The ETR and non-GAAP ETR for the full year 2020 reflected $167 million of discrete tax benefits related to settlements with taxing authorities.

Cash, Cash Equivalents and Marketable Debt Securities

As of December 31, 2020, Gilead had $7.9 billion of cash, cash equivalents and marketable debt securities compared to $25.8 billion as of December 31, 2019. During 2020, Gilead generated $8.2 billion in operating cash flow, issued senior unsecured notes in an aggregate principal amount of $7.25 billion, borrowed an aggregate principal amount of $1.0 billion under a three-year term loan facility, utilized $25.7 billion on acquisitions, net of cash acquired (including IPR D), repaid $2.5 billion of principal amount of debt, paid cash dividends of $3.4 billion and utilized $1.6 billion on share repurchases.

Gilead may choose to repay certain of its long-term debt obligations prior to maturity dates based on its assessment of current and long-term liquidity and capital requirements.