Q1 2015 Earnings Results. April 30, 2015

Q1 2015 Earnings Results April 30, 2015

Forward-looking Statements The projected financial results presented in the following slides represent management's estimates of Gilead s future financial results. Gilead cautions readers that forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially. These risks and uncertainties include: Gilead's ability to achieve its anticipated full year 2015 financial results; Gilead's ability to sustain growth in revenues for its antiviral and other programs; availability of funding for state AIDS Drug Assistance Programs (ADAPs); continued fluctuations in ADAP purchases driven by federal and state grant cycles which may not mirror patient demand and may cause fluctuations in Gilead's earnings; the possibility of unfavorable results from clinical trials involving sofosbuvir-containing products, tenofovir alafenamide, including in combination with other products, and GS-9620; Gilead's ability to initiate clinical trials in its currently anticipated timeframes; the levels of inventory held by wholesalers and retailers which may cause fluctuations in Gilead's earnings; Gilead's ability to submit new drug applications for new product candidates in the timelines currently anticipated; Gilead's ability to receive regulatory approvals in a timely manner or at all, for new and current products, including fixed-dose combination of ledipasvir and sofosbuvir in Japan; Gilead's ability to successfully commercialize its products; the risk that physicians and patients may not see advantages of these products over other therapies and may therefore be reluctant to prescribe the products; the risk that estimates of patients with HCV or anticipated patient demand may not be accurate; the risk that private and public payers may be reluctant to provide, or continue to provide, coverage or reimbursement for new products, including Sovaldi and Harvoni; Gilead's ability to successfully develop its oncology, inflammation, cardiovascular and respiratory programs, including the compounds purchased from Phenex Pharmaceuticals AG; safety and efficacy data from clinical studies may not warrant further development of Gilead's product candidates, including GS-9620; the potential for additional austerity measures in European countries that may increase the amount of discount required on Gilead's products; Gilead's ability to complete its share repurchase program due to changes in its stock price, corporate or other market conditions; Gilead s ability to pay dividends under its dividend program and the risk that its Board of Directors may reduce the amount of the dividend; fluctuations in the foreign exchange rate of the U.S. dollar that may cause an unfavorable foreign currency exchange impact on Gilead's future revenues and pre-tax earnings; and other risks identified from time to time in Gilead's reports filed with the U.S. Securities and Exchange Commission (SEC). In addition, Gilead makes estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses and related disclosures. Gilead bases its estimates on historical experience and on various other market specific and other relevant assumptions that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ significantly from these estimates. You are urged to consider statements that include the words may, will, would, could, should, might, believes, estimates, projects, potential, expects, plans, anticipates, intends, continues, forecast, designed, goal, or the negative of those words or other comparable words to be uncertain and forward-looking. Gilead directs readers to its press releases, Annual Report on Form 10-K for the year ended December 31, 2014 and other subsequent disclosure documents filed with the SEC. Gilead claims the protection of the Safe Harbor contained in the Private Securities Litigation Reform Act of 1995 for forward-looking statements. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation to update any such forward-looking statements. This presentation includes GAAP and non-gaap financial measures, a complete reconciliation between these two measures is available on the Company s website at www.gilead.com within the investor section. Management believes this non-gaap information is useful for investors, when considered in conjunction with Gilead s GAAP financial statements, because management uses such information internally for its operating, budgeting and financial planning purposes. Non-GAAP information is not prepared under a comprehensive set of accounting rules and should only be used to supplement an understanding of Gilead s operating results as reported under U.S. GAAP. 2

Q1 2015 Earnings Call Agenda Introduction Commentary Patrick O Brien, VP, Investor Relations Robin Washington, EVP and CFO Norbert Bischofberger, EVP, R&D and CSO Q&A Also: John Martin, Chairman and CEO John Milligan, President and COO Paul Carter, EVP, Commercial Operations 3

Table of Contents Discussion Slide # Robin Washington, EVP and CFO EPS, Total Revenues and Product Sales 6 10 HIV Performance 11 18 HCV Performance 19 25 R&D and SG&A Expenses 26 27 Cash Flows and Return of Capital to Shareholders 28 30 2015 Guidance 31 32 Norbert Bischofberger, EVP, R&D and CSO Pipeline and Milestones 34 37 HIV 38 42 HCV 43 47 HBV, NASH and PSC 48 50 Inflammation/Respiratory 51 52 Cardiovascular 53 54 Oncology 55 57 Appendix 58 70 4

Robin Washington EVP and Chief Financial Officer April 30, 2015

Non-GAAP Diluted EPS $3.50 Q1 2015 up 99% from Q1 2014 $3.00 $2.94 $2.50 $2.36 $2.43 $2.00 $1.84 * $1.50 $1.48 $1.00 $0.50 $0.00 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 * Includes a decrease of $0.21 per diluted share related to the cumulative catch up adjustment to the Branded Prescription Drug fee following final regulations issued by the Internal Revenue Service. Note: Non-GAAP diluted EPS excludes amounts related to acquisition, restructuring, stock-based compensation and other. 6

(In Millions) Total Revenues Q1 2015 up 52% from Q1 2014 $8,000 $7,000 $6,000 $6,535 $6,042 $7,314 $7,594 $5,000 $4,999 $4,000 $3,000 $2,000 $1,000 $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 7

(In Millions) Total Product Sales Q1 2015 up 52% from Q1 2014 $8,000 $7,000 $6,000 $6,413 $5,968 $7,222 $7,405 $5,000 $4,871 $4,000 $3,000 $2,000 $1,000 $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 8

$3,362 $4,521 $3,890 $5,086 $4,899 (in Millions) $949 $1,361 $1,234 $1,297 $1,748 Antiviral Product Sales $8,000 $7,000 $6,000 Q1 2015 up 55% from Q1 2014 $6,726 $6,012 $5,544 $6,988 U.S.: Key Metrics Inventory levels decreased sequentially for HIV products to the low end of the inventory management agreement range $5,000 $4,000 $4,509 Higher proportion of sales into Medicaid and ADAP programs in Q1 15 $3,000 Europe: $2,000 $1,000 Growth driven by HCV product launches across the region $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 U.S. Europe Other International Note: Q4 14 EU Antiviral products sales were negatively impacted by new tax legislation in France associated with HCV and Italian spending rebates. 9

in Millions European Product Sales Q1 2015 up 80% (90% excluding FX) from Q1 2014 $1,832 $1,800 $1,600 $1,436 $1,381 $1,400 $1,307 $1,200 FX impact to European revenues was unfavorable $64 million QoQ and unfavorable $102 million YoY FX impact to total international revenues (including ROW) was unfavorable $75 million QoQ and unfavorable $122 million YoY FX impact to pre-tax income was unfavorable $81 million QoQ and unfavorable $97 million YoY Q1'14 Q1'15 YoY Excl FX Atripla $237 $194 (18%) (14%) $1,000 $1,020 Eviplera $109 $145 33% 39% Stribild $24 $61 154% 167% $800 $600 $400 $200 $0 Q1'14 Q2'14 Q3'14 Q4'14 Q1'15 Truvada $323 $301 (7%) (2%) Viread $84 $80 (5%) 0% Sovaldi $163 $483 196% 213% Harvoni $0 $477 NM NM AmBisome $60 $63 5% 10% Other $20 $28 40% 63% Total $1,020 $1,832 80% 90% Note: If FX rates move by +/- 10%, revenue would be impacted by $400-$500 million on a fullyear (or annualized) basis in 2015. 10

HIV

(Estimated Patients in 000's) U.S. HIV Market Dynamics 1,400 1,200 ~1,145* ~969* 1,000 800 600 ~85% Up 5%^ ~676** ~548** 400 ~70% 200 0 HIV Infected Diagnosed On Antiretroviral Treatment ~81% On a Gilead HIV Product Sources: * CDC estimates at the end of 2011 taken from the HIV Surveillance Supplemental Report vol. 24 ** Ipsos Healthcare U.S. HIV Monitor Q4 2014. ^ Growth rate calculated as MAT (moving annual total). 12

Gilead U.S. STR Share in HIV Treatment Naïve Patients (% of Naïve Patients) 100% 80% 77% 60% 60% 40% 20% 26% 21% 17% 13% 0% On a Gilead HIV Product Gilead STRs Stribild Complera Truvada Atripla Q4 12 Q4 13 Q414 Base: All initiations within each quarter. Source: Ipsos Healthcare HIV U.S. Scope & Monitor Q4 2014. 13

Top Prescribed HIV Regimens U.S. Rank Naïve All Patients Europe Big-5 Rank Naïve All Patients 1 Stribild Atripla 1 Eviplera Atripla 2 Complera Stribild 2 Stribild Eviplera 3 Atripla Complera 3 Atripla Truvada + other 3 rd Agent 4 Other Agent Truvada + other 3 rd Agent 4 Truvada + other 3 rd Agent Truvada + other 3 rd Agent 5 Truvada + other 3 rd Agent Truvada + other 3 rd Agent 5 Truvada + other 3 rd Agent Stribild Source: Ipsos Healthcare HIV U.S. Therapy Monitor Q4 2014. EU Naïve Source: Ipsos Healthcare HIV EU Scope Q4 2014. EU All Patient Source: Ipsos Healthcare HIV EU Monitor Q3 2014. Single tablet regimens 14

$187 $230 $278 $319 $282 $24 (In Millions) $31 $38 $61 $52 Stribild Product Sales $500 $400 $300 $200 $100 $0 $215 Q1 2015 up 66% from Q1 2014 $327 $270 $385 $356 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 U.S. Europe Other International U.S.: Key Metrics* Captured 26% of naïve HIV patient share Number two most prescribed HIV regimen across all treated patients Sequential increase in demand offset by inventory reduction Europe: Captured 15% of naïve HIV patient share in Big-5 Number two most prescribed HIV regimen in both naïve and switch patients Launched in Big-5 as well as seventeen additional countries *Sources: U.S. data from Ipsos Healthcare HIV U.S. Therapy Monitor Q4 2014. EU data from Ipsos Healthcare HIV EU Scope Q4 2014. Note: Stribild is indicated for the treatment of HIV-1 infection in antiretroviral treatment naïve patients. 15

$131 $153 $183 $196 $163 $109 $132 (In Millions) $134 $145 $138 Complera/Eviplera Product Sales $500 Q1 2015 up 27% from Q1 2014 Key Metrics* U.S. (Complera): $400 $300 $251 $299 $330 $348 $320 Captured 21% of naïve HIV patient share Third most prescribed HIV regimen across all patients Sequential increase in demand offset by inventory reduction Europe (Eviplera): $200 Captured 23% of naïve HIV patient share in Big-5 $100 Preferred status in France, Germany, Italy and UK Most switched to HIV regimen in Big-5 $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 U.S. Europe Other International *Sources: U.S. data from Ipsos Healthcare HIV U.S. Therapy Monitor Q4 2014. EU data from Ipsos Healthcare HIV EU Scope Q4 2014. 16

$490 $578 $621 $668 $494 (In Millions) $237 $194 $234 $223 $194 Atripla Product Sales $1,000 $750 $500 $250 $0 $780 Q1 2015 down 6% from Q1 2014 (Recently downgraded in DHHS guidelines) $870 $895 $925 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 U.S. Europe Other International $734 Note: Efavirenz (the active pharmaceutical component in Atripla purchased from Bristol-Myers Squibb) accounted for approximately 37% of Atripla sales in Q1 2015 which represented $268 million to be paid to BMS. U.S.: Europe: Key Metrics* Most prescribed HIV regimen with 24% of all treated patients Captured 13% of naïve HIV patient share Decrease due to shift in demand to new STRs and sequential reduction in inventory Most prescribed HIV regimen with 21% of all treated patients Captured 15% of naïve HIV patient share** *Sources: U.S. data from Ipsos Healthcare HIV U.S. Therapy Monitor Q4 2014. EU data from Ipsos Healthcare HIV EU Therapy Monitor Q3 2014 & Ipsos Healthcare HIV EU Scope Q4 2014. **Note: In the EU Atripla does not have an indication for the treatment of naïve patients and there is no Atripla promotion concerning treatment naïve patients. 17

$368 $399 $472 $548 $409 (In Millions) $323 $338 $301 $327 $287 Truvada Product Sales $1,000 $750 $500 $250 $0 Q1 2015 up 1% from Q1 2014 $897 $877 $806 $760 $771 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 U.S. Europe Other International U.S.: Key Metrics* Captured 30% of all treated HIV patients Captured 17% of naïve HIV patient share Decrease due to shift in demand to new STRs and sequential reduction in inventory Europe: Most prescribed HIV product with 33% of all treated patients Captured 30% of naïve HIV patient share *Sources: U.S. data from Ipsos Healthcare HIV U.S. Therapy Monitor Q4 2014. EU data from Ipsos Healthcare HIV EU Therapy Monitor Q3 2014 & Ipsos Healthcare HIV EU Scope Q4 2014. 18

HCV

HCV Patients Treated with a Sofosbuvir-based Regimen in the U.S. and Europe Big-5 Cumulative Patients Treated (in thousands) ~260,000 patients or 4% of the estimated 6.6 million infected population (U.S. ~4.0 million and Big-5 ~2.6 million) have been treated with a sofosbuvir-based regimen since December 2013 300 ~260 250 200 150 100 Big-5 U.S. 50 - Q4 Q1 Q2 Q3 Q4 Q1 2013 2014 2015 Note: Sovaldi was approved in the U.S on December 6, 2013 and in the EU on January 17, 2014. Harvoni was approved in the U.S. on October 10, 2014 and in the EU on November 18, 2014. Graph illustrates the cumulative number of patients treated with a Gilead HCV drug since the approval of Sovaldi. 20

Global Prevalence of HCV Estimated to Be 185 Million (1) HCV Prevalence <1% 1-1.9% 2-2.9% >3% Not tested HCV Prevalence Core Markets (2) Emerging Markets (3) Region US Europe Big-5 Japan Europe Asia Latin Other America All Genotypes (Millions) 4.0 2.6 1.1 6.7 70.8 5.4 Genotype 1 (%) 79% 63% 67% 65% 39% 68% Sources: 1) WHO Guidelines for the Screening, Care, and Treatment of Persons with Hepatitis C Infection, April 2014 2) Gilead Forecast (2011 prevalence estimate). 3) Cornberg, Sievert, and Kershenobich, et al. 2011. Country populations from 2009 World Bank estimates. 21

Profile of U.S. HCV Patients that are Intended for Treatment with a Sofosbuvir-based Regimen (January March 2015*) Genotype Fibrosis Score GT 3, 7% GT 2, 12% GT 1, 81% F3-F4, 44% F0-F2, 56% Patient Type Treatment Experienced, 18% *Data Source: Gilead market research January 1 - March 15, 2015. Treatment Naïve, 82% Note: Fibrosis score is based on the METAVIR scoring system. Intended for treatment is based on scripts written, not scripts filled. 22

Simplifying and Advancing the Treatment for HCV Patients $972 million in worldwide sales in Q1 2015 Approved in the U.S., European Union and Japan Approved for genotype 1-4 HCV infected patients* *Approved for genotype 1-6 patients in the European Union and genotype 2 in Japan. **Approved for genotype 1, 3 (certain subgroups) and 4 in the European Union. $3.6 billion in sales in Q1 2015 mostly in the U.S. Approved in the U.S. and European Union Approved for genotype 1 HCV infected patients** 23

$2,274 $3,480 $2,796 $1,732 $972 (in Millions) $2,107 $3,579 Total HCV Product Sales $5,000 $4,500 $4,000 $3,500 Q1 2015 up 19% from Q4 2014 $3,481 $3,839 $4,551 Key Metrics Increase from Q4 14 driven by increase in HCV patient volumes partially offset by higher level of rebates $3,000 $2,500 $2,000 $1,500 $2,274 $2,816 In Q1 15 approximately 70,000 and 21,000 patient starts with a Gilead HCV regimen in the U.S. and Europe, respectively $1,000 $500 $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 Sovaldi Harvoni 24

Total HCV Sales by Geography (in millions, except percentages) Q1 2015: $4,551 (100% YoY Growth) U.S.: $3,437 (76% of Total) (64% YoY Growth) Europe: $960 (21% of Total) (489% YoY Growth) Other International: $154 (3% of Total) Note: Amounts may not sum due to rounding. 25

(In Millions) Non-GAAP R&D Expenses $1,000 $900 $800 $700 $600 $500 $400 $300 $200 Q1 2015 up 17% from Q1 2014 $899 $265 * $586 $558 $542 $651 Key Metrics Higher R&D expenses in Q1 15 over Q1 14 driven primarily by continued progression and expansion of our product pipeline, in particular in the liver disease and oncology areas Sequential decrease from Q4 14 primarily due to onetime M&A related costs $100 $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 R&D One-time items * One-time items of $265 million for M&A related costs and purchase of a FDA Priority Review Voucher. Note: Non-GAAP R&D expenses exclude amounts related to acquisition, restructuring, stockbased compensation and other. 26

(In Millions) Non-GAAP SG&A Expenses $1,000 $900 $800 $700 $600 $500 $400 $300 $200 $500 Q1 2015 up 20% from Q1 2014 $888 $799 $337 $155 $570 * * $600 Key Metrics Higher SG&A in Q1 15 over Q1 14 driven by ongoing growth of the business, including commercial expansion of our HCV products Q1 15 includes favorable adjustment for Branded Prescription Drug (BPD) fee based on receipt of preliminary invoice from the IRS $100 $0 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 SG&A BPD fee catch-up * Q3 14 and Q4 14 include a total catch-up of $492 million for BPD fee due to an industry-wide methodology adjustment. Note: Non-GAAP SG&A expenses exclude amounts related to acquisition, restructuring, stockbased compensation and other. 27

(In Millions) Operating Cash Flows Key Metrics $6,000 $5,000 $5,701 Higher Operating Cash Flow in Q1 2015 driven primarily by: $4,000 $3,000 $2,000 $1,000 $0 $4,185 $4,044 $3,021 $1,568 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 Collections related to initial Harvoni sales in Q4 2014 Growth in current quarter sales Higher accrued government and other rebates for Harvoni uptake that remained unpaid as of March 31, 2015 and are anticipated to be paid in future quarters 28

2015 Share Repurchase Activity During the period from January 2010 through March 2015, ~54% of free cash flow was utilized to purchase and retire ~26% of shares outstanding Type of Repurchase Dollar Amount* (In Millions) Shares Repurchased Average Purchase Price Q1 2015 Open Market $3,000 29,593,030 $101.38 As of March 31, 2015, we completed the $5 billion repurchase plan authorized in May 2014. Under the total program, we repurchased 48.8 million shares with an average purchase price $102.36 per share. An additional $15 billion share repurchase program was authorized in January 2015. *Excludes commissions. 29

Return of Capital to Shareholders Share repurchase programs - $5 billion May 2014 share repurchase program completed as of March 31, 2015 - $15 billion January 2015 share repurchase program initiated in April 2015 Cash dividend program - Declared the Company s first quarterly dividend of $0.43 per share, $1.72 annually - Dividend payable June 29, 2015 to stockholders of record as of the close of business on June 16, 2015 30

Full Year 2015 Guidance (in millions, except percentages and per share amounts) All Products* All Products* Initially provided 2/3/2015 Updated on 4/30/2015 Net Product Sales $ 26,000 $ 27,000 $ 28,000 $ 29,000 Non-GAAP** Product Gross Margin 87% 90% 87% 90% R&D Expenses $ 3,000 $ 3,300 $ 3,000 $ 3,300 SG&A Expenses $ 3,000 $ 3,300 $ 3,000 $ 3,300 Effective Tax Rate 18.0% 20.0% 18.0% 20.0% Diluted EPS Impact of Acquisition-Related and Stock- Based Compensation Expenses $ 0.82 $ 0.87 $ 0.82 $0.87 *This guidance is subject to a number of uncertainties, including, but not limited to, the level and speed of market acceptance of Harvoni, the pricing and rate of reimbursement for Harvoni, the amount of patient warehousing prior to approval, the anticipated number of patients with HCV, the overall patient mix, the rate of decrease in wholesaler inventories of Sovaldi as more patients are prescribed Harvoni and the launch timing and market acceptance of competitive drugs. **Non-GAAP product gross margin, expenses and effective tax rate exclude amounts related to acquisition, restructuring, stock-based compensation and other. 31

Full Year 2015 Guidance (in millions, except percentages and per share amounts) Projected product gross margin GAAP to non-gaap reconciliation: GAAP projected product gross margin Acquisition related-expenses Non-GAAP projected product gross margin* Initially provided on 2/3/2015; Reiterated on 4/30/2015 84% - 86% 3% - 4% 87% - 90% Projected research and development expenses GAAP to non-gaap reconciliation: GAAP projected research and development expenses Acquisition related-expenses Stock-based compensation expenses Non-GAAP projected research and development expenses $3,323 - $3,663 (141) - (171) (182) - (192) $3,000 - $3,300 Projected selling, general and administrative expenses GAAP to non-gaap reconciliation: GAAP projected selling, general and administrative expenses Acquisition related-expenses Stock-based compensation expenses Non-GAAP projected selling, general and administrative expenses $3,235 - $3,545 - (235) - (245) $3,000 - $3,300 Projected diluted EPS impact of acquisition-related and stock-based compensation expenses: Acquisition related-expenses Stock-based compensation expenses Projected diluted EPS impact of acquisition-related and stock-based compensation expenses $0.60 - $0.63 0.22-0.24 $0.82 - $0.87 *Stock-based compensation expenses have a less than one percent impact on non-gaap projected product gross margin. 32

Norbert Bishofberger EVP, R&D and CSO April 30, 2015

Pipeline Product Candidates HIV STR of EVG/cobicistat/FTC/TAF Phase 1 2 3 U.S. and EU Regulatory Submission Regulatory Submissions F/TAF (emtricitabine/tenofovir alafenamide) - Switch Studies U.S. and EU Regulatory Submission STR of rilpivirine/ftc/taf - Bioequivalence Studies GS-9883 (integrase inhibitor) GS-9620 (TLR-7 agonist) Liver Diseases HCV STR of SOF/GS-5816 (pan-genotypic NS5B/NS5A inhibitors) GS-9857/SOF/GS-5816 (pan-genotypic NS3 protease inhibitor) HBV TAF (nucleotide reverse transcriptase inhibitor) GS-4774 (Tarmogen T cell immunity stimulator) GS-9620 (TLR-7 agonist) NASH/Other Liver Diseases Simtuzumab (monoclonal antibody) - NASH Simtuzumab (monoclonal antibody) - Primary Sclerosing Cholangitis GS-4997 (ASK-1 inhibitor) - NASH Cardiovascular Ranolazine (late sodium current inhibitor) - Incomplete Revascularization Post PCI GS-6615 (late sodium current inhibitor) - LQT-3 Syndrome GS-4997 (ASK-1 inhibitor) - PAH Ranolazine/Dronedarone FDC - Paroxysmal Atrial Fibrillation GS-6615 (late sodium current inhibitor) - Hypertrophic Cardiomyopathy GS-6615 (late sodium current inhibitor) - Ventricular Tachycardia/Ventricular Fibrillation GS-6615 (late sodium current inhibitor) - Ischemic Heart Disease 34

Pipeline Product Candidates (continued) Hematology/Oncology Idelalisib (PI3K delta inhibitor) - Frontline and Relapsed Refractory CLL Idelalisib (PI3K delta inhibitor) - Relapsed Refractory inhl Momelotinib (JAK inhibitor) - Myelofibrosis Idelalisib (PI3K delta inhibitor) - Frontline inhl Momelotinib (JAK inhibitor) - Pancreatic Cancer GS-5745 (MMP9 mab inhibitor) - Gastric Cancer Entospletinib (Syk inhibitor) - Hematological Malignancies GS-4059 (BTK inhibitor) - B-cell malignancies GS-9901 (PI3K delta inhibitor) - Hematological Malignancies GS-5745 (MMP9 mab inhibitor) - Solid Tumors GS-5829 (BET inhibitor) - Solid Tumors/DLBCL Inflammation/Respiratory GS-5806 (fusion inhibitor) - Respiratory Syncytial Virus Simtuzumab (monoclonal antibody) - IPF GS-4997 (ASK-1 inhibitor) - Diabetic Nephropathy GS-5745 (MMP9 mab inhibitor) - Ulcerative Colitis GS-5745 (MMP9 mab inhibitor) - Crohn's Disease GS-5745 (MMP9 mab inhibitor) - COPD GS-5745 (MMP9 mab inhibitor) - Rheumatoid Arthritis GS-9876 (Syk inhibitor) - Rheumatoid Arthritis Phase 1 2 3 Regulatory Submissions GS-4059: Formerly ONO-4059. 35

Significant Pipeline Milestones Anticipated in 2015 HIV TAF Cobicistat Q2 15 Q2 15 Q3 15 Q4 15 Q4 15 Submitted NDA to the U.S. FDA for F/TAF Submitted MAA to EMA for F/TAF Submit U.S. NDA for rilpivirine/f/taf U.S. FDA approval of E/C/F/TAF European Commission approval of E/C/F/TAF Q1 15 FDA approved DRV/COBI and ATV/COBI GS-9883 Q1 15 Initiated Phase 2 study Oncology Idelalisib Q2 15 Initiate Phase 2 study for Idelalisib in frontline inhl GS-5745 Q3 15 Initiate Phase 3 study in gastric cancer Momelotinib 2H 15 Initiate Phase 3 study in front line metastatic pancreatic cancer Inflammation/Respiratory Simtuzumab Q2 15 Completed enrollment of IPF Phase 2 study 36

Significant Pipeline Milestones Anticipated in 2015 (Continued) HCV Sofosbuvir Q1 15 Japan PMDA approved for GT 2 HCV patients Ledipasvir/ Sofosbuvir GS-9857/ Sofosbuvir/GS-5816 Sofosbuvir/GS-5816 2H 15 2H 15 Q3 15 Q4 15 Japan PMDA approval for GT 1 HCV patients Anticipate top line data from Phase 2 studies Anticipate top line data from Phase 3 studies Submit U.S. NDA and EU MAA HBV GS-4774 2H 15 Anticipate topline data from virally suppressed patients in Phase 2 study GS-9620 2H 15 Anticipate topline data from Phase 2 study Cardiovascular GS-6615 Q1 15 Q1 15 Ranolazine Q1 15 Initiated Phase 3 study in LQT-3 syndrome Initiated Phase 2/3 study in hypertrophic cardiomyopathy Completed enrollment in Phase 3 study in incomplete revascularization post PCI 37

HIV

TAF STR Results from Phase 3 Studies in Treatment-Naïve HIV-1 Patients E/C/F/TAF is non-inferior to Stribild Study 104 & 111: 92.4% of E/C/F/TAF patients compared to 90.4% of Stribild patients (at week 48) Statistically significant difference in estimated glomerular filtration rate (egfr) Statistically significant smaller median percentage decrease from baseline in lumbar spine and hip bone mineral density compared to Stribild patients U.S. NDA and EU MAA submitted U.S. PDUFA date November 5, 2015 39

E/C/F/TAF U.S. and EU Filings Supported by Five Studies Adult Tx Naive Patients (n = 866) Adult Tx Naive Patients (n = 867) Largest, most comprehensive HIV filing to date ~3,500 patients involved in five studies Adult Switch Patients (n = 1,472) Adults with Mild/Moderate Renal Impairment (n = 253 Tx Naïve or Tx Exp) Adolescents (n = 50 Tx Naïve) 40

Additional TAF-Based STRs to follow E/C/F/TAF FTC/TAF U.S. NDA submitted on April 7, 2015 EU MAA submitted on April 21, 2015 Rilpivirine/FTC/TAF (R/F/TAF) Anticipated NDA filing in Q3 2015 Darunavir/cobicistat/FTC/TAF (D/C/F/TAF) Development and commercialization will be led by Janssen First STR containing a protease inhibitor 41

Innovation in HIV Beyond TAF GS-9883 A novel once daily integrase inhibitor which does not require boosting Currently in Phase 2 GS-9620 (TLR-7 agonist) Explored as part of a potential cure for HIV Induced viremia in rhesus macaques suppressed on therapy 42

HCV

SOF Studies Across All Genotypes SOF/GS-5816 in four Phase 3 studies ongoing Genotypes 1-6 Treatment-naïve and experienced patients Includes cirrhotic and severe patient populations 12-week duration and 24-week comparator arms Data anticipated in Q3 2015 GS-9857/SOF/GS-5816 Phase 2 studies are ongoing exploring 6, 8 and 12-week durations across all genotypes in patients with and without cirrhosis 44

Gilead s Presence at EASL 2015 38 Gilead-sponsored abstracts Sofosbuvir (SOF) Ledipasvir/sofosbuvir (LDV/SOF) GS-5816 (pan-genotypic NS5A inhibitor) GS-9857 (pan-genotypic protease inhibitor) GS-9620 (TLR-7 agonist) GS-9857 combined with SOF/GS-5816 demonstrated pan-genotypic potential Data for SOF and LDV/SOF in patients with advanced liver disease Data from BOSON trial demonstrated high cure rates for genotype 2 and 3 patients European Association for the Study of the Liver (April 22-26, 2015) GT 3 treatment-experienced patients with cirrhosis achieved an SVR12 of 86% with SOF + PEG/RBV for 12 weeks 45

Sovaldi and Harvoni Included in EASL & AASLD Recommendations Across All HCV Genotypes EASL guidelines recommend Sovaldi with other direct acting antivirals (DAAs) AASLD guidelines updated to include Harvoni Evidence clearly supports treatment in all HCV-infected persons except those with limited life expectancy For GT 1a treatment-experienced cirrhotics: Harvoni + RBV for 12 weeks vs. Viekira Pak for 24 weeks For GT 1a treatment-naive cirrhotics: Harvoni for 12 weeks vs. Viekira Pak for 24 weeks 46

Regulatory Filing in Japan GT 1: Harvoni dosed for 12 weeks NDA submitted in September 2014 Phase 3 study results in genotype 1 HCV-infected patients o Achieved SVR12 of 100% Approval anticipated Q3 15 47

HBV, NASH and PSC

HBV Development Cure Programs GS-9620 (TLR-7 agonist) o Phase 2 study ongoing o In a preclinical woodchuck model, GS-9620 successfully cleared woodchuck HBV and decreased s-ag GS-4774 (Tarmogen T cell immunity stimulator) o Therapeutic vaccine using a yeast-based vector to express different antigens o Two Phase 2 studies ongoing TAF for the chronic treatment of HBV Two Phase 3 studies fully enrolled 49

NASH and PSC Primary Sclerosing Cholangitis (PSC) Simtuzumab Phase 2 study fully enrolled NASH (Nonalcoholic Steatohepatitis) Simtuzumab Phase 2 study fully enrolled o Endpoint of HVPG (hepatic venous pressure gradient) GS-9674 (FXR agonist) clinical studies to be initiated o Small molecule non bile acid derivative GS-4997 (ASK-1 inhibitor) currently in Phase 1 o Future studies planned to explore a combination of GS-4997 and simtuzumab 50

Inflammation/Respiratory

Inflammation and Respiratory Development Simtuzumab for Idiopathic Pulmonary Fibrosis (IPF) Phase 2 study fully enrolled GS-5806 (fusion inhibitor) for Respiratory Syncytial Virus (RSV) Phase 2 studies ongoing GS-5745 (MMP9 mab inhibitor) Plans to advance to Phase 2/3 in the 2H 2015 for ulcerative colitis Currently in Phase 1 for chronic obstructive pulmonary disease (COPD), rheumatoid arthritis (RA) and Crohn s disease 52

Cardiovascular

GS-6615 (Late Sodium Current Inhibitor) Once daily, low dose, highly specific late sodium current inhibitor LQT-3 Syndrome Phase 3 Hypertrophic Cardiomyopathy Phase 2/3 Ventricular Tachycardia/Ventricular Fibrillation Phase 2 Ischemic Heart Disease Phase 2 Drug induced QT prolongation and LQT-2 syndrome Phase 2 54

Oncology

Gilead Oncology R&D Focus Intracellular Signaling Idelalisib (PI3K- inhibitor) o On going Phase 3 studies in CLL and NHL GS-9973 (SYK inhibitor) o Phase 2 study in relapsed-refractory hematologic malignancies Momelotinib (JAK 1,2 inhibitor) o Phase 3 studies in myelofibrosis o Phase 3 study for front-line metastatic pancreatic cancer to be initiated in Q3 GS-4059 (a once-daily BTK inhibitor) o Collaboration with Ono Pharmaceutical o Phase I results promising in B-cell malignancies o Focus on combination studies Extracellular Matrix GS-5745 (anti-mmp9 antibody) for inflammation and solid tumors o MMP9 promotes inflammation and tumor growth o Phase 3 study in gastric cancer to be initiated in Q3 o Phase 1 study for pancreatic carcinoma ongoing 56

Zydelig: A First-In-Class PI3K Delta Inhibitor U.S. Gilead s first approval in oncology in July 2014 Accelerated approval for relapsed follicular lymphoma (FL) and small lymphocytic lymphoma (SLL) Approved for relapsed chronic lymphocytic leukemia (CLL) Q1 2015 revenue of $14 million EU European Commission approval in September 2014 Approved for relapsed FL and CLL* Pricing and reimbursement process ongoing Q1 2015 revenue of $12 million *For the treatment of CLL, Zydelig can be used as first-line treatment in the presence of 17p deletion or TP53 mutation in patients unsuitable for chemo-immunotherapy. 57

Appendix Slides April 30, 2015

Gilead's Efforts to Increase Global Access HIV and HCV Generic Licensing Entered into licensing agreements for HIV with eight India-based generic manufacturers in 2006 Announced non-exclusive licensing agreements for HCV with eleven Indiabased generic manufacturers in 2014 and 2015 o o Includes Sovaldi and Harvoni For distribution in 91 developing countries, where more than 100 million people estimated living with HCV Medicines Patent Pool (MPP) Announced new agreement with MPP to expand access to the investigational drug TAF for HIV and HBV, contingent on U.S. regulatory approval MPP can sub-license TAF to generic drug companies who may manufacture and distribute in 112 developing countries Gilead s Access Operations & Emerging Markets Combined access efforts reached over 7 million HIV patients in low and middle-income countries 59

Financial Highlights: Q1 2015 (in millions, except percentages and per share amounts) Q1 2014 Q1 2015 % Change Net Product Sales $4,871 $7,405 52% Antiviral Products 4,509 6,988 55% HCV 2,274 4,551 100% HIV and Other Antiviral 2,235 2,437 9% Other Products* 362 417 15% Non-GAAP Costs and Expenses** $1,669 $1,925 15% COGS 611 674 10% Product Gross Margin 87% 91% R&D 558 651 17% SG&A 500 600 20% Operating Margin 67% 75% Non-GAAP Net Income $2,488 $4,604 85% Non-GAAP Diluted EPS $1.48 $2.94 99% * Other Products comprised primarily of Letairis, Ranexa, AmBisome, Zydelig, Cayston and Lexiscan. **Non-GAAP costs and expenses, net income and diluted EPS exclude amounts related to acquisition, restructuring, stock-based compensation and other. 60

Product Sales by Geography (in millions, except percentages) Q1 2015: $7,405 (52% YoY Growth) U.S.: $5,209 (70% of Total) (44% YoY Growth) Europe: $1,832 (25% of Total) (80% YoY Growth) Other International: $364 (5% of Total) (61% YoY Growth) Note: Amounts may not sum due to rounding. 61

Select Product Sales (in millions) Q1 2014 Q2 2014 Q3 2014 Q4 2014 FY 2014 Q1 2015 % Change from Q1 2014 Harvoni NA NA $20 $2,107 $2,127 $3,579 NM Viread $211 $261 $275 $311 $1,058 $234 11% Letairis $123 $145 $146 $181 $595 $151 23% Ranexa $111 $123 $132 $144 $510 $117 5% AmBisome $92 $94 $98 $104 $388 $85 (8%) Zydelig NA NA $6 $17 $23 $26 NM Other* $36 $39 $42 $50 $167 $38 6% *Other comprised primarily of Cayston and Lexiscan. 62

(In Millions) Total Royalty, Contract and Other Revenues Q1 2015 up 48% from Q1 2014 $200 $189 $175 $150 $125 $128 $122 $73 $100 $75 $50 $25 $76 $64 $52 $58 $74 $68 $92 $74 $116 $0 $6 $18 Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 Tamiflu Other 63

Non-GAAP Product Gross Margins Key Metrics 100% 75% 87.4% 88.7% 86.9% 88.3% 90.9% Higher Non-GAAP Product Gross Margins Q1 15 over Q1 14 driven primarily by favorable product mix 50% 25% 0% Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 Note: Non-GAAP product gross margins exclude amounts related to acquisition, restructuring, stock-based compensation and other. 64

Non-GAAP Operating Margins Key Metrics 100% 75% 50% 25% 66.6% 71.9% 62.6% 65.2% 74.7% Higher Non-GAAP Operating Margins in Q1 15 over Q1 14 driven primarily by: - Higher gross margin from favorable product mix - Lower operating expense growth than revenue growth 0% Q1 14 Q2 14 Q3 14 Q4 14 Q1 15 Note: Non-GAAP operating margins exclude amounts related to acquisition, restructuring, stock-based compensation and other. 65

GAAP to Non-GAAP Diluted Earnings Per Share Reconciliation Q1 2015 GAAP Diluted EPS $2.76 All Acquisition-Related Expenses $0.13 Stock-Based Compensation Expenses $0.04 Non-GAAP Diluted EPS $2.94 Note: Amounts may not sum due to rounding. 66

Non-GAAP Effective Tax Rate Q1 2014 Q1 2015 Non-GAAP Effective Tax Rate 23.2% 16.9% The decrease from Q1 2014 is primarily due to an increase in HCV revenue. Note: Non-GAAP Effective Tax Rate excludes amounts related to acquisition, restructuring, stock-based compensation and other. 67

Outstanding Debt (in billions) Dec. 31, 2014 Mar. 31, 2015 Senior Unsecured Notes $11.95 $11.95 Convertible Notes $0.50 $0.45 Total Debt 1 $12.45 $12.40 1 - Debt amount shown at face value. Total interest expense and amortization from all issued debt expected to be approximately $130 million per quarter in 2015 or $520 million for the full year 2015. 68

Dilution from Outstanding Convertible Notes 2016 Notes Total Dilution * Average share price Q1 2015 $101.54 Convertible Notes ** (Current Outstanding) $454M Conversion Price $22.71 Q1 2015 Share Dilution 16.2M 16.2M Warrants Warrant Exercise Price $30.05 Q1 2015 Share Dilution 38.8M 38.8M Total Q1 2015 Dilution from Convertible Notes and Warrants *** 55.0M * May not sum/recalculate due to rounding. ** At issuance, the amount outstanding on the 2016 convertible notes was $1.25B. *** Represents ~3.5% of diluted non-gaap shares outstanding. 69

Other Selected Financial Information (in millions, except days sales outstanding) Dec. 31, 2014 Mar. 31, 2015 Cash, Cash Equivalents & Marketable Securities $11,726 $14,514 Inventories $1,386 $1,908 Days Sales Outstanding* (Accounts Receivable) 48 42 Share Repurchases During the Quarter** $2,000 $3,000 Interest Expense and Other Income (Expense), net Diluted Shares Used in Per Share Calculation for the Quarter (Non-GAAP) Diluted Shares Used in Per Share Calculation for the Quarter (GAAP) ($100) ($132) 1,596 1,568 1,597 1,569 Basic Shares Outstanding 1,506 1,488 * Decrease in Q1 15 DSO driven by collections made in the quarter related to Q4 14 Harvoni sales in the U.S. As we continue to launch HCV products in ex-u.s., particularly in Southern Europe, DSO is expected to increase in the future. ** Excludes commissions. 70

Q1 2015 Earnings Results April 30, 2015