Gilead Sciences, Inc. () is an American biopharmaceutical company headquartered in Foster City, California, that focuses on researching and developing antiviral drugs used in the treatment of HIV/AIDS, hepatitis B, hepatitis C, influenza, and COVID-19. It also develops medicines in therapeutic areas such as oncology and inflammation and cell therapy.
In 1987, Michael L. Riordan founded the company under the name Oligogen. The original name was a reference to oligonucleotides, small strands of DNA used to target genetic sequences. Gilead held its initial public offering in 1992, and successfully developed drugs including Tamiflu and Vistide that decade.
In the 2000s, Gilead began evolving from a biotechnology company into a large pharmaceutical company, through acquisitions and investments, acquiring several subsidiaries. Gilead is a member of the Nasdaq-100 and the S&P 100.
The company has faced criticism over its business practices, including extremely high pricing of drugs such as Sovaldi and Truvada in the United States relative to production cost and cost in the developing world.
History
Foundation
In June 1987, Gilead Sciences was originally founded under the name Oligogen by Michael L. Riordan, a medical doctor. Riordan graduated from Washington University in St. Louis, the Johns Hopkins School of Medicine, and the Harvard Business School. The idea for Gilead began as a research project at Menlo Ventures, where Michael was an associate. Three scientific advisers worked with Riordan to create the company: Peter Dervan of Caltech, Doug Melton of Harvard, and Harold M. Weintraub of the Fred Hutchinson Cancer Research Center, along with H. Dubose Montgomery, one of Menlo Ventures founders. Riordan served as CEO from the company's founding until 1996. Menlo Ventures subsequently made the first investment in Gilead of $2 million. Riordan also recruited scientific advisers, including Harold Varmus, a Nobel laureate who later became Director of the National Institutes of Health, and Jack Szostak, recipient of the Nobel Prize for Physiology or Medicine in 2009.
The company's primary therapeutic focus was in antiviral medicines, a field that piqued Riordan's interest after he contracted dengue fever. Riordan recruited Donald Rumsfeld to join the board of directors in 1988, followed by Benno C. Schmidt, Sr., Gordon Moore, and George P. Shultz. Riordan tried to recruit Warren Buffett as an investor and board member but was unsuccessful.
The company focused its early research on making small strands of DNA (oligomers, or more particularly, oligonucleotides) to target specific genetic code sequences – that is, antisense therapy, a form of gene therapy. According to Riordan, he had always wanted to use the name Gilead Sciences all along. Still, he used Oligogen as a temporary name because he needed to deal with a trademark clearance issue with a California nonprofit organization that was already using the word Gilead in its name. He had first heard of the Balm of Gilead when he read Lanford Wilson's play Balm in Gilead while in medical school, then learned that naturally occurring acetylsalicylic acid (aspirin) had been found in modern times in a willow tree species from that part of that world, and was therefore inspired to name his company Gilead. After founding Oligogen, he contacted the nonprofit about the naming issue and secured the right to use the Gilead Sciences name in exchange for a $1,000 donation.
By 1988, the company had moved its headquarters to Foster City's Vintage Park neighborhood, where it has been based ever since. The company began to develop small molecule antiviral therapeutics in 1991, when the company in-licensed a group of nucleotide compounds including tenofovir.
Riordan later recalled that Gilead's first decade as a startup was an extremely stressful experience for him, as a young venture capitalist serving for the first time as the founder, chairman, and chief executive officer of his own biotech company. The new company had no products and very little income, and narrowly escaped going out of business on several occasions: "It was touch and go for a long time". Finding a way for Gilead to make money was Riordan's top priority "every second of the day for eight years".
1990–1999: IPO
Gilead's antisense intellectual property portfolio was sold to Ionis Pharmaceuticals. Gilead debuted on the NASDAQ in January 1992. Its initial public offering raised $86.25 million in proceeds.
In June 1996, Gilead launched Vistide (cidofovir injection) for the treatment of cytomegalovirus (CMV) retinitis in patients with AIDS.
In January 1997, Donald Rumsfeld was appointed chairman, but left the board in January 2001 when he was appointed United States Secretary of Defense during George W. Bush's first term as president.
In March 1999, Gilead acquired NeXstar Pharmaceuticals of Boulder, Colorado. At the time, NeXstar's annual sales of $130 million was three times Gilead's sales; it sold AmBisome, an injectable fungal treatment, and DaunoXome, an oncology drug taken by HIV patients. That same year, Roche announced FDA approval of Tamiflu (oseltamivir) for the treatment of influenza. Tamiflu was originally discovered by Gilead and licensed to Roche for late-phase development and marketing.
One reason for entering into the Tamiflu licensing agreement was that with only 350 employees, Gilead still did not yet have the capability to sell its drugs directly to overseas buyers. To avoid having to license future drugs in order to access international markets, Gilead simply acquired the 480-employee NeXstar, which had already built its own sales force in Europe to market AmBisome there.
2000 to 2009
Viread (tenofovir) achieved first approval in 2001 for the treatment of HIV.
In 2002, Gilead changed its corporate strategy to focus exclusively on antivirals, and sold its cancer assets to OSI Pharmaceuticals for $200 million.
In December 2002, Gilead and Triangle Pharmaceuticals announced that Gilead would acquire Triangle for around $464 million; Triangle's lead drug was emtricitabine that was near FDA approval, and it had two other antivirals in its pipeline. The company also announced its first full year of profitability. Later that year, Hepsera (adefovir) was approved for the treatment of chronic hepatitis B, and Emtriva (emtricitabine) for the treatment of HIV.
During this era, Gilead completed its gradual evolution from a biotech startup into a pharmaceutical company. The San Francisco Chronicle noted that by 2003, the Gilead corporate campus in Foster City had expanded to "seven low-slung sand-colored buildings around a tiny lake on which ducks happily paddle." Like many startups, Gilead originally leased its space, but in 2004, the company paid $123 million to buy all its headquarters buildings from its landlords. However, even as Gilead developed its ability to distribute and sell its own drugs, it remained distinct from most pharmaceutical companies in terms of its strong reliance on subcontracting most of its manufacturing to contract manufacturing organizations.
In 2004, during the Avian flu pandemic scare, Gilead Sciences' revenue from Tamiflu almost quadrupled to $44.6m as more than 60 national governments stockpiled the antiviral drug, though the firm had made a loss in 2003 before concern about the flu started. As stocks soared, US Defense Secretary and Pentagon chief Donald Rumsfeld sold shares of the company, receiving more than $5 million in capital gains, while still maintaining up to $25m-worth of shares by the end of the year. Sales of Tamiflu almost quadrupled again in 2005, to $161.6m, during which time the share price tripled. A 2005 report showed that, in all, Rumsfeld owned shares worth up to $95.9m, from which he got an income of up to $13m.
In 2006, the company acquired Corus Pharma, Inc. for $365 million. The acquisition of Corus signaled Gilead's entry into the respiratory arena. Corus was developing aztreonam lysine for the treatment of patients with cystic fibrosis who are infected with Pseudomonas aeruginosa.
In July 2006, the U.S. Food and Drug Administration (FDA) approved Atripla, a once a day single tablet regimen for HIV, combining Sustiva (efavirenz), a Bristol-Myers Squibb product, and Truvada (emtricitabine and tenofovir disoproxil), a Gilead product.
Gilead purchased Raylo Chemicals, Inc. in November 2006, for a price of US$133.3 million. Raylo Chemical, based in Edmonton, Alberta, was a wholly owned subsidiary of Degussa AG, a German company. Raylo Chemical was a custom manufacturer of active pharmaceutical ingredients and advanced intermediates for the pharmaceutical and biopharmaceutical industries.
Later in the same year, Gilead acquired Myogen, Inc. for $2.5 billion (then its largest acquisition). With two drugs in development (ambrisentan and darusentan), and one marketed product (Flolan) for pulmonary diseases, the acquisition of Myogen has solidified Gilead's position in this therapeutic arena. Under an agreement with GlaxoSmithKline, Myogen marketed Flolan (epoprostenol sodium) in the United States for the treatment of primary pulmonary hypertension. Additionally, Myogen was developing (in Phase 3 studies) darusentan, also an endothelin receptor antagonist, for the potential treatment of resistant hypertension.
Gilead expanded its move into respiratory therapeutics in 2007 by entering into a licensing agreement with Parion for an epithelial sodium channel inhibitor for the treatment of pulmonary diseases, including cystic fibrosis, chronic obstructive pulmonary disease and bronchiectasis.
In 2009, the company acquired CV Therapeutics, Inc. for $1.4 billion, bringing Ranexa and Lexiscan into Gilead. Ranexa is a cardiovascular drug used to treat chest pain related to coronary artery disease, with both of these products and pipeline building out Gilead's cardiovascular franchise. Later that year, the company was named one of the Fastest Growing Companies by Fortune.
2010 to 2019
In 2010, the company acquired CGI Pharmaceuticals for $120 million, expanding Gilead's research expertise into kinase biology and chemistry. Later that year, the company acquired Arresto Biosciences, Inc. for $225 million, obtaining developmental-stage research for treating fibrotic diseases and cancer.
In February 2011, the company acquired Calistoga Pharmaceuticals for US$375 million ($225 million plus milestone payments). The acquisition boosted Gilead's oncology and inflammation areas. Later that year, Gilead made its most important acquisition – and by then most expensive – with the US$10.4 billion purchase of Pharmasset, Inc. This transaction helped cement Gilead as the leader in treatment of the hepatitis C virus by giving it control of sofosbuvir (see below).
In October 2011, Gilead broke ground on a massive multi-year expansion of its 17-building headquarters campus in Foster City. By replacing eight one or two-story buildings with seven new structures ranging as tall as 10 stories, Gilead nearly doubled its headquarters real estate footprint from about 620,000 square feet to about 1.2 million square feet.
On July 16, 2012, the FDA approved Gilead's Truvada for prevention of HIV infection (it was already approved for treating HIV). The pill was a preventive measure (PrEP) for people at high risk of getting HIV through sexual activity.
In 2013, the company acquired YM Biosciences, Inc. for $510 million. The acquisition brings drug candidate CYT387, an orally administered, once-daily, selective inhibitor of the Janus kinase (JAK) family, specifically JAK1 and JAK2, into Gilead's oncology pipeline. The JAK enzymes have been implicated in myeloproliferative diseases, inflammatory disorders, and certain cancers.
In 2015, the company made a trio of acquisitions:
It bought Phenex Pharmaceuticals for $470 million. Its Farnesoid X receptor (FXR) program used small-molecule FXR agonists in the treatment of liver diseases such as non-alcoholic steatohepatitis.
It bought EpiTherapeutics for $65 million. This acquisition gave Gilead first-in-class small molecule inhibitors of histone demethylases involved in regulating gene transcription in cancer.
It paid $425 million for a 15% equity stake in Galapagos NV, with additional payments for Gilead to license the experimental anti-inflammatory drug filgotinib, which may treat rheumatoid arthritis, ulcerative colitis, and Crohn's disease.
In 2016, the company acquired Nimbus Apollo, Inc. for $400 million, giving Gilead control of the compound NDI-010976 (an ACC inhibitor) and other preclinical ACC inhibitors for the treatment of non-alcoholic steatohepatitis and for the potential treatment of hepatocellular carcinoma. Also in 2016, the company was named the most generous company on the 2016 Fortune list of The Most Generous Companies of the Fortune 500. Charitable donations to HIV/AIDS and liver disease organizations totaled over 440 million in 2015.
In August 2017, the company announced it would acquire Kite Pharma for $11.9 billion, equating to $180 cash per share, a 29% premium over the closing price of the shares. The deal was Gilead's entry into the cell therapy market and added a chimeric antigen receptor T cell (CAR-T) therapy candidate to the company's portfolio. By 2022 this acquisition had led to two marketed products for lymphoma: Yescarta and Tecartus. In November, the company announced it will acquire Cell Design Labs for up to $567 million, after it indirectly acquired a stake of 12.2% via the Kite Pharma deal.
On May 9, 2019, the U.S. Department of Health and Human Services announced that Gilead Sciences will donate Truvada, the only drug approved to prevent infection with H.I.V., for free to 200,000 patients annually for 11 years. On December 3, 2019, HHS explained how the government would distribute the donated drugs. HHS Secretary Alex Azar explained that the U.S. government will pay Gilead $200 per bottle for 30 pills for costs associated with getting the drug from factories into the eventual hands of patients.
2020-
In March 2020, the company announced it would acquire Forty Seven Inc. for $95.50 a share ($4.9 billion in total). On April 7, 2020, Gilead completed acquisition of Forty Seven, Inc. for "$95.50 per share, net to the seller in cash, without interest, or approximately $4.9 billion in the aggregate."
In June 2020, Bloomberg reported that AstraZeneca Plc had made a preliminary approach to Gilead for a potential merger, worth almost $240 billion. In the same month, the company announced it would acquire a 49.9% stake in privately held Pionyr Immunotherapeutics Inc for $275 million.
In September 2020, Gilead announced it had reached a deal to acquire Immunomedics for $21 billion ($88 per share), gaining control of the cancer treatment Trodelvy (Sacituzumab govitecan-hziy) – a first-in-class Trop-2 antibody-drug conjugate. In December, the business announced it would acquire German biotech, MYR GmbH, for €1.15 billion plus up to a further €300 million. MYR focuses on the treatment of chronic hepatitis delta virus.
In November 2021, the company was added to the Dow Jones Sustainability World Index.
In January 2022, Gilead pulled its cancer drug Zydelig (idelalisib) from its accelerated approval in relapsed follicular B-cell non-Hodgkin lymphoma (FL) and relapsed small lymphocytic leukemia (SLL).
In September, the company completed its acquisition of MiroBio for $405 million.
In February 2023, the business, through Kite Pharma completed its acquisition of Tmunity Therapeutics. In May, the business announced it would acquire XinThera and its small molecule inhibitors.
In February 2024, the company acquired CymaBay Therapeutics, and in September, paid Genesis Therapeutics $35 million for AI-based drug discovery work.
In May 2025, Gilead Sciences announced it would pay $10 million for sole ownership of arenavirus immunotherapies for hepatitis B (HBV) and HIV resulting from the company's collaboration with Hookipa Pharma.
In December 2025, it was announced that Gilead Sciences had agreed to acquire RP-3467, a polymerase theta (Polθ) ATPase inhibitor, from Repare Therapeutics for total consideration of up to US$30 million. The agreement includes an upfront payment of US$25 million and up to an additional US$5 million contingent on the completion of specified technology transfer activities.
Acquisition history
Treatments for hepatitis C
The drug sofosbuvir had been part of the 2011 acquisition of Pharmasset. In 2013, the FDA approved this drug, under the trade name Sovaldi, as a treatment for the hepatitis C virus. Forbes magazine ranked Gilead its number 4 drug company, citing a market capitalization of US$113 billion and stock appreciation of 100%, and describing their 2011 purchase of Pharmasset for $11 billion as "one of the best pharma acquisitions ever". Deutsche Bank estimated Sovaldi sales in the year's final quarter would be $53 million, and Barron's noted the FDA approval and subsequent strong sales of the "potentially revolutionary" drug as a positive indicator for the stock.
On July 11, 2014, the United States Senate Committee on Finance investigated Sovaldi's high price ($1,000 per pill; $84,000 for the full 12-week regimen). Senators questioned the extent to which the market was operating "efficiently and rationally", and committee chairman Ron Wyden (D-Oregon) and ranking minority member Chuck Grassley (R-Iowa) wrote to CEO John C. Martin asking Gilead to justify the price for this drug. The committee hearings did not result in new law, but in 2014 and 2015, due to negotiated and mandated discounts, Sovaldi was sold well below the list price. For poorer countries, Gilead licensed multiple companies to produce generic versions of Sovaldi; in India, a pill's price was as low as $4.29.
Gilead later combined Sovaldi with other antivirals in single-pill combinations. First, Sovaldi was combined with ledipasvir and marketed as Harvoni. This treatment for hepatitis C cures the patient in 94% to 99% of cases (HCV genotype 1). By 2017, Gilead was reporting drastic drops in Sovaldi revenue from year to year, not only because of pricing pressure but because the number of suitable patients decreased. Later single-pill combinations were Epclusa (with velpatasvir) and Vosevi (with velpatasvir and voxilaprevir).
Finances
For the fiscal year 2017, Gilead Sciences reported earnings of US$4.628 billion and annual revenue of US$26.107 billion, a decline of 14.1% over the previous fiscal cycle. Gilead Sciences's shares traded at over $70 per share, and its market capitalization was valued at US$93.4 billion in October 2018.