Eli Lilly: The Pharma Giant Behind Mounjaro and Zepbound

Eli Lilly is one of the oldest and most storied pharmaceutical companies in the world. Its legacy of breakthroughs has shaped modern medicine: from mass-producing insulin to leading today's fight against diabetes and obesity. With over 150 years of operation, the company stands at the absolute center of the global pharmaceutical industry. Let's see how we got here and what may lie ahead.

• Insulin breakthrough: In the 1920s, Eli Lilly became the first company to commercialize and mass-produce insulin, catapulting the firm onto the global stage.

• R&D investments: Over the past three years, the company has reinvested approximately 25% of its revenue into R&D, strengthening its position as a leader in pharmaceutical innovation.

• GLP-1 focus: In recent years, much of the spotlight on Eli Lilly has centered on its treatments for type 2 diabetes and obesity, where it is competing head-to-head with Danish rival Novo Nordisk.

The story of what we now know as the world's largest pharmaceutical company began in the second half of the 19th century with a former Colonel in the Union Army in the American Civil War. After the war ended, the Colonel, named Eli Lilly, decided to pursue a career in pharmaceutical chemistry. Following two short-lived partnerships in the drugstore business, he decided to strike out on his own. In 1876, he founded a pharmaceutical manufacturing company in Indianapolis: Eli Lilly and Company.

Under Lilly's leadership, the firm grew quickly from a small operation into a business known for early innovations like gelatin-coated pills and fruit-flavored medicines, designed to make treatment more effective and easier for patients to take. By the late 1870s, annual sales had reached tens of thousands of dollars, and by the 1880s, the company had grown to over 100 employees, becoming one of Indiana's most prominent businesses.

A defining moment in Eli Lilly's history came in the early 1920s with a breakthrough that would go on to save millions of lives: insulin. In 1921, researchers in Toronto discovered that insulin could treat diabetes. Shortly thereafter, Eli Lilly & Co. went into a partnership with the researchers to become the first company to commercialize and mass-produce it for global use.

Marketed under the name Iletin, Eli Lilly's insulin became the world's first widely available therapy for diabetes. The achievement not only transformed diabetes care but also established it as a pioneer in biologic medicines, marking the company's transition from regional manufacturer to global pharmaceutical giant.

Following this breakthrough, Eli Lilly's role in global healthcare continued to expand. Another major milestone came in 1955, when the company became the first to mass-produce the polio vaccine developed by Jonas Salk, helping to scale one of the most important public health achievements of the century.

In the decades after World War II, the company broadened its focus beyond insulin and vaccines, investing heavily in research and manufacturing. It began developing antibiotics and other essential medicines, steadily building a reputation as one of the leading pharmaceutical companies in the U.S.

In the second half of the 20th century, Eli Lilly introduced several blockbuster drugs that carried it into a new era. Notably, in 1986, the company launched Prozac (fluoxetine), a breakthrough antidepressant that became a cultural phenomenon as one of the first widely used SSRI medications. This was followed by other successful neuroscience drugs like Zyprexa (olanzapine) in 1996 for schizophrenia and bipolar disorder, and Cymbalta (duloxetine) in 2004 for depression and anxiety.

Nearly 150 years since its founding, Eli Lilly's therapies are now marketed in more than 125 countries, and the company has grown into a global pharma giant with a market capitalization exceeding $700 billion.

Today, Eli Lilly & Co. is involved in every step of the pharmaceutical value chain – from research and drug discovery to large-scale manufacturing and distribution of medicines.

As of 2024, the company employed approximately 47,000 people globally, including roughly 11,000 in R&D roles focused on next-generation therapies. During the last three years (2022-2024), roughly 25% of its revenue has been plowed back into R&D to fuel its long-term ambition (sourced through Quartr Pro).

While the company's early growth was largely organic, it has increasingly relied on strategic acquisitions and partnerships to strengthen its portfolio. This combination of internal development and external expansion has helped it surpass long-standing industry leaders. As of 2025, Eli Lilly is the most valuable pharmaceutical company in the world, ahead of the likes of Johnson & Johnson, Pfizer, Merck & Co., Novo Nordisk, AbbVie, and Roche.

Eli Lilly, like all major pharmaceutical companies, operates under the close watch of regulators, policymakers, and the public. The U.S. healthcare environment, in particular, can be both a growth engine and a source of risk. Whether it's Congressional debates on drug pricing, evolving FDA approval standards, or Medicare coverage decisions, government action can have large effects on its business or the industry as a whole overnight.

One persistent structural risk is the so-called patent cliff, which is the expiration of exclusivity on blockbuster drugs, often leading to steep revenue declines as lower-cost generics or biosimilars enter the market. For companies like Eli Lilly, the challenge lies in maintaining pipeline momentum and bringing new therapies to market quickly enough to offset those losses.

In recent years, Eli Lilly has become a central player in the high-stakes “GLP-1 race”, the competition to dominate the fast-growing market for drugs treating type 2 diabetes and obesity. GLP-1 receptor agonists and related therapies have redefined treatment for these conditions, offering both improved blood sugar control and significant weight loss.

The trend was initially led by Danish rival Novo Nordisk, whose semaglutide-based drugs – Ozempic (for diabetes) and Wegovy (for obesity) – gained rapid traction after their launches in 2017 and 2021. But Eli Lilly wasn't far behind. Having introduced one of the first GLP-1s in the 2000s, the company returned to the spotlight with Mounjaro (tirzepatide), approved in 2022 for diabetes, followed by Zepbound, its obesity-specific version, in 2023.

Since then, demand for GLP-1 therapies has surged well beyond diabetic patients, with millions seeking new options for medical weight loss. The rapid uptake even triggered intermittent supply shortages, creating space for compounded alternatives from companies such as Hims & Hers.

Although Eli Lilly generated over $16 billion in revenue from these labels in 2024 (accounting for more than a third of its total revenue), expectations are that this could just be the beginning of a decade-long growth trend for the company. If Eli Lilly is to end this megatrend as the winner remains to be seen. But to say the least, they're very well positioned.

Further reading: David A. Ricks: Eli Lilly's Chairman and CEO

Eli Lilly's evolution from a small Midwestern drugmaker to the world's most valuable pharmaceutical company is rooted in some of the most significant milestones in modern healthcare. From pioneering insulin nearly a century ago, to the leader in the ongoing GLP-1 race. If its momentum is any guide, its next chapter is one to watch closely.