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Gilead Sciences, Inc.

BiotechnologyFounded 1987
Reviewed by Swet Parvadiya
Company data updated: October 2026

Founders

Who Founded Gilead Sciences?

Michael L. Riordan · Founded 1987 · HQ today: Foster City, California

Who founded Gilead Sciences?

Gilead Sciences was founded by Michael L. Riordan in 1987. It is now led by Daniel P. O'Day.

Founders
Michael L. Riordan
Founded
1987
Headquarters
Foster City, California
Number of founders
1
Current CEO
Daniel P. O'Day (since 2019)
Where was Gilead Sciences founded?
Gilead Sciences was founded in Foster City, California in 1987.
When was Gilead Sciences founded?
Gilead Sciences was founded in 1987.
Who started Gilead Sciences?
Gilead Sciences was founded by Michael L. Riordan.
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.

Michael L. Riordan

Co-founder 1987

Background

Michael L. Riordan, a physician with an MD from Johns Hopkins and an MBA, founded Gilead Sciences in 1987 while at Menlo Ventures. He served as CEO until 1996, took the company public in 1992, and steered it toward antiviral drugs.

Role at Gilead Sciences, Inc.

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.

Gilead Sciences, Inc.: CEO & Leadership History

Full timeline →

Daniel P. O'Day

Chairman and Chief Executive Officer

2019 – Present

O'Day's leadership has transformed Gilead from a specialized virology company into a diversified, global biopharmaceutical leader. While his aggressive oncology acquisitions required upfront capital expenditure, they provided the company with the strong, diverse clinical pipeline necessary to survive the eventual patent expirations of its core HIV medications. His strategic vision has stabilized the company's long-term revenue projections and restored investor confidence.

John F. Milligan

Chief Executive Officer

2016 – 2018

During his nearly three decades at Gilead, he helped build the company's HIV franchise before orchestrating the monumental financial success of the HCV cures.

John C. Martin

Chief Executive Officer

1996 – 2016

As CEO for two decades, he took Gilead from a small biotech startup to a pharmaceutical behemoth, generating tens of billions in revenue from Truvada and Sovaldi.

Michael Riordan

Chief Executive Officer

1987 – 1996

He successfully navigated the brutal early stages of biotech funding, taking the company public in 1992 and establishing its foundational viral research culture.

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Gilead Sciences, Inc. vs Moderna, Inc. Leadership →Overview

Keep researching Gilead Sciences

Who Founded Gilead Sciences? FAQ

Who founded Gilead Sciences and in what year was the company established?

Gilead Sciences was founded in June 1987 in Foster City, California, by Dr. Michael L. Riordan, a 29-year-old physician and venture capitalist.

What inspired Dr. Michael L. Riordan to establish Gilead Sciences?

While working in the Peace Corps and clinics in the Philippines, Dr. Riordan contracted dengue fever, a painful tropical viral illness with no effective treatment. This personal experience inspired him to create a specialized pharmaceutical company dedicated exclusively to discovering novel antiviral medicines.

Who were the key co-founding scientists and early advisors who built Gilead with Michael Riordan?

Dr. Riordan recruited top scientists including Dr. Peter Dervan (pioneering Caltech organic chemist), Dr. Douglas Froehler, Dr. Mark Matteucci (antisense oligonucleotide specialists), and business leader Jack Martin. Prominent figures like Donald Rumsfeld served on Gilead's early Board of Directors.

What was Gilead Sciences' initial scientific research focus in the late 1980s?

Gilead initially focused on antisense oligonucleotides, synthetic genetic sequences designed to bind to viral RNA or DNA to block disease-causing protein synthesis, before pivoting toward broad-spectrum nucleotide analog chemistry, which yielded its large antiviral breakthroughs.

Where does the name 'Gilead Sciences' originate and what is its symbolic meaning?

The company was named after the ancient 'Balm of Gilead', a celebrated medicinal plant resin referenced in historical and biblical texts as a universal healing compound, symbolizing the company's founding mission to create life-saving cures for human disease.

When did Gilead Sciences complete its initial public offering (IPO)?

Gilead Sciences completed its initial public offering in January 1992, raising $86 million on the NASDAQ exchange under the ticker symbol GILD to fund clinical development of small-molecule antiviral and cardiovascular drug candidates.

What was Gilead's first commercial product approved by the FDA?

Gilead's first FDA-approved commercial product was Vistide (cidofovir injection), approved in 1996 for the treatment of cytomegalovirus (CMV) retinitis in patients suffering from advanced AIDS, establishing Gilead's clinical credibility in antiviral medicine.

How did early venture capital backing support Gilead's foundational laboratory research?

Early venture funding from Menlo Ventures and venture capital pioneer Venrock provided the financial runway for Dr. Riordan to assemble a high-quality chemistry team in Foster City and acquire foundational nucleotide analog patents from European academic institutes.

Who founded Gilead Sciences?

It was founded by Dr. Michael Riordan. However, the company was truly built into a massive global empire by John C. Martin, the legendary CEO who ran Gilead from 1996 to 2016. (Interestingly, former US Secretary of Defense Donald Rumsfeld served as Chairman of Gilead in the 1990s).

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Content is for informational purposes only. Not financial advice. Data sourced from SEC filings, annual reports, and public records. See our full disclaimer and methodology.