Gilead Sciences, Inc.
Company History
Gilead Sciences History: Founding, Growth & Key Milestones
Founded 1987 in Foster City, California
When was Gilead Sciences founded?
Gilead Sciences was founded in 1987 in Foster City, California by Michael L. Riordan, making it 39 years old.
- Founded
- 1987
- Founding place
- Foster City, California
- Founders
- Michael L. Riordan
- Headquarters today
- Foster City, California
- Milestones documented
- 12 (1987–2026)
- Current CEO
- Daniel P. O'Day
- Acquisitions
- 8
| Year | Event |
|---|---|
| 1987 | Founding of Gilead Sciences |
| 1992 | Initial Public Offering |
| 2001 | Approval of Viread |
| 2003 | Acquisition of Triangle Pharmaceuticals |
| 2006 | Atripla Approved |
| 2011 | Acquisition of Pharmasset |
| 2013 | Sovaldi Approved |
| 2017 | Acquisition of Kite Pharma |
| 2020 | Acquisition of Immunomedics |
| 2024 | PURPOSE 1 Trial Results |
| 2025 | Yeztugo Approval and FY2025 Results |
| 2026 | Arcellx, Tubulis and Ouro Acquisitions |
- Where was Gilead Sciences founded?
- Gilead Sciences was founded in Foster City, California in 1987.
- Who founded Gilead Sciences?
- Gilead Sciences was founded by Michael L. Riordan.
- When did Gilead Sciences start?
- Gilead Sciences was founded in 1987.
- How old is Gilead Sciences?
- Gilead Sciences is 39 years old as of 2026.
Founding Story
Michael Riordan, a physician with an MBA, founded Gilead in 1987 after working at Menlo Ventures, which provided early funding. A bout of dengue fever had convinced him that the world needed better antiviral drugs. The company, first called Oligogen, began with antisense technology and was renamed after the biblical Balm of Gilead. It went public in 1992 and later licensed nucleotide analogs that became the basis of its HIV medicines.
Founders
Michael L. Riordan
Michael Riordan founded Gilead in Foster City, California, in 1987. Before that he trained in medicine and worked in venture capital at Menlo Ventures, which provided early funding. A case of dengue fever contracted while abroad shaped his interest in antiviral drugs. The company, originally named Oligogen, started with antisense technology and was renamed Gilead after the biblical Balm of Gilead. Riordan led the 1992 IPO and in-licensed nucleotide analogs that later became the foundation of Gilead's HIV and hepatitis B drugs, including tenofovir. He hired John C. Martin, who succeeded him as CEO in 1996. Michael L. Riordan was born in 1957.
Key Milestones
Founding of Gilead Sciences
Michael L. Riordan founded the company, originally called Oligogen, in Foster City, California, to develop antisense and antiviral therapies.
Source: en.wikipedia.orgInitial Public Offering
Gilead went public on Nasdaq, giving it the capital to keep developing antiviral drugs.
Source: en.wikipedia.orgApproval of Viread
The FDA approved Viread (tenofovir disoproxil fumarate), the nucleotide analog that became the backbone of Gilead's HIV franchise.
Source: en.wikipedia.orgAcquisition of Triangle Pharmaceuticals
Gilead acquired Triangle Pharmaceuticals, gaining emtricitabine, which it combined with tenofovir to create Truvada.
Source: en.wikipedia.orgAtripla Approved
The FDA approved Atripla, the first once-daily single-tablet HIV regimen, in July 2006.
Source: en.wikipedia.orgAcquisition of Pharmasset
Gilead acquired Pharmasset for about $11 billion, gaining sofosbuvir, the basis of hepatitis C cures Sovaldi and Harvoni.
Source: en.wikipedia.orgSovaldi Approved
The FDA approved the hepatitis C drug Sovaldi in December 2013.
Source: en.wikipedia.orgAcquisition of Kite Pharma
Gilead acquired Kite Pharma for about $11.9 billion, adding the CAR-T therapy Yescarta.
Source: en.wikipedia.orgAcquisition of Immunomedics
Gilead acquired Immunomedics for about $21 billion, adding the Trop-2 antibody-drug conjugate Trodelvy.
Source: en.wikipedia.orgPURPOSE 1 Trial Results
Twice-yearly lenacapavir showed zero HIV infections among women in the PURPOSE 1 prevention trial.
Source: en.wikipedia.orgYeztugo Approval and FY2025 Results
The FDA approved Yeztugo (lenacapavir) in June 2025 as the first twice-yearly HIV PrEP option. Gilead finished 2025 with $29.4 billion in revenue and $14.3 billion in Biktarvy sales.
Source: investors.gilead.comArcellx, Tubulis and Ouro Acquisitions
Gilead closed acquisitions of Arcellx (April, about $7.8 billion implied equity value), Tubulis (May, $3.15 billion upfront) and Ouro Medicines ($1.675 billion upfront).
Source: gilead.comMajor Acquisitions
Arcellx, Inc.
2026Full ownership of anito-cel, a BCMA-directed CAR-T therapy for multiple myeloma developed with Kite.
Tubulis GmbH
2026Next-generation antibody-drug conjugate platform from a Munich-based biotech.
Ouro Medicines
2026Expand the inflammation pipeline, acquired together with Lakefront.
CymaBay Therapeutics
2024Gain seladelpar (Livdelzi) for primary biliary cholangitis.
Immunomedics, Inc.
2020Gilead acquired Immunomedics for $21 billion to gain control of the Sacituzumab govitecan (Trodelvy) ADC platform, establishing a dominant position in solid tumor oncology.
Kite Pharma, Inc.
2017Gilead acquired Kite Pharma for $11.9 billion to establish a dominant position in autologous CAR-T cell therapy with Yescarta and expand its presence in oncology.
Pharmasset, Inc.
2011Gilead acquired Pharmasset for $11 billion to secure the nucleotide analog platform responsible for Sovaldi and Harvoni, the curative hepatitis C therapies.
Forty Seven, Inc.
2020Gilead acquired Forty Seven for $4.9 billion to gain control of the CD47 blocker magrolimab, a novel oncology asset targeting myelodysplastic syndromes and acute myeloid leukemia.
Keep researching Gilead Sciences
Gilead Sciences Company History FAQ
What are the defining eras in the historical journey of Gilead Sciences since 1987?
Gilead's history is defined by its founding oligonucleotide research era (1987-1995), the HIV single-tablet revolution under John Martin (1996-2010), the historic Hepatitis C cure era with Sovaldi/Harvoni (2011-2016), the expansion into cell therapy with Kite Pharma (2017), and the oncology and pandemic response era under Daniel O'Day (2019-present).
How did Gilead transform HIV treatment with the launch of the first single-tablet regimen, Atripla, in 2006?
In 2006, Gilead partnered with Bristol-Myers Squibb to launch Atripla, the world's first once-daily single-tablet complete regimen for HIV. Combining three antiretroviral drugs into a single pill, Atripla transformed HIV from a fatal diagnosis requiring dozens of daily pills into a manageable chronic condition.
What was the global impact of Gilead's discovery and development of Tamiflu (oseltamivir)?
In 1996, Gilead scientists invented oseltamivir (Tamiflu), a potent oral neuraminidase inhibitor for influenza. Licensed to Roche for global manufacturing and distribution, Tamiflu became the essential frontline antiviral stockpiled worldwide by governments to combat avian flu and H1N1 influenza pandemics.
How did Gilead's tenofovir prodrug breakthrough (TAF vs. TDF) extend its HIV leadership?
Gilead engineered tenofovir alafenamide (TAF), a novel prodrug that delivers the active antiviral agent into lymphoid cells at one-tenth the dose of older tenofovir disoproxil fumarate (TDF). TAF significantly reduced renal and bone mineral density side effects, powering next-generation blockbusters Genvoya, Descovy, and Biktarvy.
What was the significance of the FDA approval of Truvada for HIV PrEP in 2012?
In 2012, the FDA approved Truvada as the world's first medicine for pre-exposure prophylaxis (PrEP) to prevent HIV infection in at-risk individuals, marking a historic public health milestone that reduced new HIV infection rates worldwide.
How did Gilead respond to global manufacturing demand for Veklury during COVID-19?
Gilead scaled manufacturing of remdesivir from virtually zero to millions of treatment courses within months, invested hundreds of millions in chemical synthesis plants, and established voluntary royalty-free licensing agreements with generic manufacturers across India, Pakistan, and Egypt to supply over 125 developing nations.
What philanthropic and access initiatives has Gilead established to fight global epidemics?
Through the Gilead COMPASS Initiative, the Gilead Science Foundation, and global licensing partnerships, Gilead has distributed affordable generic HIV and HCV medicines to over 14 million people in resource-limited nations and committed hundreds of millions to eliminate healthcare disparities in underserved communities.
What is Gilead Sciences' long-term corporate vision for therapeutic breakthroughs by 2030?
Gilead's vision is to deliver 10+ transformative therapies by 2030, achieve functional cures for HIV and Hepatitis B, establish long-acting lenacapavir as the global standard for HIV prevention, and generate more than one-third of total company revenues from its expanding oncology portfolio.
How did Gilead start?
Gilead Sciences was founded in 1987 by Michael Riordan, a medical doctor who was only 29 years old. Originally operating out of a small clinic, Riordan wanted to focus entirely on antiviral drugs (which were largely ignored by massive pharmaceutical companies at the time). Their first major global success was developing Tamiflu, which they licensed to Roche.
Related Companies
Compare Gilead Sciences, Inc. History With Competitors
Related Strategic History
Compare founding milestones and corporate evolution
Explore Gilead Sciences
Core profile pages, founders and related research hubs for this company.