Eli Lilly makes prescription medicines and sells them in roughly 90 countries. Patients take these medicines repeatedly, often for years, which means each new prescription generates revenue again and again. The company operates in one business segment: human pharmaceutical products. Its biggest earners today are Mounjaro and Zepbound, two medicines based on the same active ingredient, tirzepatide. Mounjaro treats type 2 diabetes. Zepbound treats obesity and a breathing condition called obstructive sleep apnea. Together they made up 56 percent of total revenues in 2025. Beyond those two, Lilly sells cancer medicines like Verzenio, insulin products like Humalog and Humulin, and immunology treatments like Taltz. Revenue comes from selling these products to wholesalers, who pass them to pharmacies, hospitals, and clinics. Lilly also runs LillyDirect, a digital platform that connects patients to independent pharmacies for direct delivery. The diagram below traces where the money goes.
How Eli Lilly Makes Money
flowchart TD
A["R&D: Discover & Develop
New Medicines"] --> B["Manufacturing & Production
Multiple Facilities Worldwide"]
B --> C["Product Portfolio
$61.0B product revenue"]
C --> D["Sales Through Distributors
& LillyDirect Platform"]
D --> E["Revenue from Patients
$65.2B total revenue"]
E --> F["Gross Profit
83% margin"]
F --> G["Operating Cash Flow
$16.8B"]
G --> H["Reinvestment in R&D
& Acquisitions"]
H --> A
C --> I["Patent & Data Protection
Market Exclusivity"]
I --> J["Pricing Power &
Competitive Position"]
J --> E
D --> K["Marketing & Access
Programs to Healthcare Providers"]
K --> D
Five years of financial data tell a clear story of acceleration. Revenue was $28.3 billion in 2021. It barely moved in 2022, reaching $28.5 billion. Then tirzepatide changed everything. Revenue jumped to $34.1 billion in 2023, then to $45.0 billion in 2024, and then to $65.2 billion in 2025. That is more than a doubling in two years.
Eli Lilly Annual Revenue (2021 to 2025)
Revenue in billions of US dollars. The sharp rise from 2023 onward reflects the commercial launch and rapid uptake of Mounjaro and Zepbound.
Gross margin tells a complementary story. In 2021, Lilly kept about 74 cents of every revenue dollar after the direct cost of making its products. By 2025 that figure had risen to about 83 cents. Higher-margin products like Mounjaro and Zepbound, combined with improved manufacturing efficiency, are driving that improvement. Operating cash flow followed the same path, rising from $7.4 billion in 2021 to $16.8 billion in 2025. Free cash flow matched operating cash flow in each year.
$16.8B
Operating cash flow generated in 2025, up from $7.4B in 2021
There is one notable counterweight to that cash generation. Net debt has grown significantly, from $13.1 billion in 2021 to $35.2 billion in 2025. The company spent $7.8 billion on capital expenditures in 2025 alone, up from $5.1 billion in 2024, as it builds new factories to keep up with demand. Lilly has also paid out $3.0 billion for acquired research programs in 2025 and repurchased $4.1 billion of its own shares. The cash engine is powerful, but the company is spending heavily at the same time.
2023
milestone
Tirzepatide becomes a commercial force
Zepbound received approval for obesity in the US in late 2023, joining Mounjaro which had launched for type 2 diabetes in 2022. By 2025, the two brands together generated $36.5 billion in revenue, making tirzepatide one of the fastest-growing pharmaceutical products on record. This single molecule now defines the financial profile of the entire company.
That concentration is also the sharpest risk. Six products generated over 82 percent of total revenues in 2025. Mounjaro and Zepbound alone accounted for 56 percent. If either faced a safety concern, a supply failure, or a sudden shift in insurance coverage, the impact on total revenue would be immediate and large. In July 2025, CVS Caremark stopped listing Zepbound as a preferred medicine on some insurance plans, which is an early example of how quickly access can change.
What patent expiry means for a drug company
When a medicine's patent expires, other companies can make identical cheaper versions called generics or biosimilars. These copies typically capture a large share of patients very quickly and the original maker's revenue from that product can fall sharply in a short time. Drug companies depend on new patented medicines to replace the revenue they lose when older patents expire.
Patent risk is real and dated. Trulicity, a diabetes medicine that was a major revenue driver before tirzepatide arrived, faces compound patent expiry in the US in 2027. The US government has already selected Trulicity for price controls effective 2028, under a law called the Inflation Reduction Act. Jardiance, a diabetes and heart medicine developed in partnership with Boehringer Ingelheim, faces a similar government-set price effective 2026. Verzenio, the breast cancer medicine, was also selected for government pricing effective 2028. The company acknowledges that more products will likely be selected in future years.
56%
Share of 2025 revenues from Mounjaro and Zepbound alone
Manufacturing is another pressure point. Lilly is building new factories at speed to meet demand for tirzepatide and future obesity medicines. Delays in that expansion could limit supply and cap revenue growth. The company also relies on suppliers based in China for certain materials, creating exposure to tariffs and geopolitical disruption. Separately, counterfeit and compounded versions of its incretin medicines circulate in the market, which can confuse patients and divert sales.
What GLP-1 and incretin medicines are
GLP-1 stands for glucagon-like peptide-1, a hormone the body produces naturally to regulate blood sugar and appetite. Medicines that mimic or enhance this hormone, called incretin medicines, can lower blood sugar in diabetics and reduce body weight in people with obesity. Tirzepatide, the active ingredient in Mounjaro and Zepbound, targets two such hormones at once.
Lilly is building a pipeline to extend beyond tirzepatide. Orforglipron, a pill-based obesity and diabetes medicine, has been submitted for regulatory review in the US, EU, and Japan. A pill would remove the need for injections, potentially opening access to patients who avoid needles. Retatrutide, another medicine targeting obesity and related conditions, is in late-stage trials. The Alzheimer's medicine Kisunla has been approved in the US, EU, and Japan. The company has also acquired programs in cancer and cardiovascular disease. Research and development spending reached $13.3 billion in 2025, up 21 percent from 2024.
$13.3B
Research and development spending in 2025, up 21% from the prior year
In November 2025, Lilly reached preliminary agreements with the US government to lower Medicaid prices for its medicines and to adopt a more balanced pricing approach across developed countries. The final terms of those agreements were still being negotiated at the time of filing.
The Bet
Mounjaro and Zepbound keep growing fast enough, for long enough, to fund the pipeline that must replace them before their own patents and competitive pressures erode their value. Tirzepatide's US compound patent runs to 2036, which gives the business over a decade of potential exclusivity. But the obesity medicine market is attracting intense competition, insurance coverage barriers are real and growing, and government price controls are already reaching into the portfolio. If tirzepatide's growth slows sooner than the pipeline matures, or if orforglipron and the next generation of cardiometabolic medicines fail to win approval or gain broad coverage, the revenue base that funds $13 billion a year in research spending loses its foundation.
Open question
Lilly has built one of the fastest-growing revenue profiles in the pharmaceutical industry on the back of a single molecule. The pipeline is large and active, and cash flow has expanded dramatically. But 56 percent of revenue rests on two brand names for one ingredient, government price controls are already touching the portfolio, and the company is carrying $35.2 billion in net debt while spending heavily on factories and research. Can the next generation of medicines, led by orforglipron and the broader obesity and cardiovascular pipeline, grow large enough to sustain the company's trajectory if tirzepatide faces earlier-than-expected competitive or regulatory pressure?
Compiled · 10-K · FY2025
Product Revenue Concentration
Six products generated over 82 percent of total revenues in 2025, with Mounjaro and Zepbound alone accounting for 56 percent. If any of these major products lose patent protection, face safety concerns, experience reduced demand, or encounter supply problems, the company could see sudden and significant revenue declines.
Intellectual Property Loss
Trulicity will lose significant patent protection in the next few years. When products lose patent protection, generic competitors can quickly enter the market and cause rapid, severe revenue declines. The company depends on continually developing new products to replace revenues lost to patent expirations.
U.S. Government Price Controls
In August 2023, the U.S. government set prices for Jardiance at significant discounts to list price, effective in 2026. In January 2026, Trulicity and Verzenio were also selected for government-set prices effective in 2028. The company expects more products will be selected in future years, which will accelerate revenue erosion across the portfolio.
Obesity Medicine Access and Pricing Risk
Mounjaro and Zepbound represent 56 percent of 2025 revenues and the company expects obesity medicines to grow significantly. However, securing insurance coverage and patient access faces major obstacles. In July 2025, CVS Caremark stopped covering Zepbound as preferred on some plans, and many international payers do not cover obesity medicines, forcing patients to pay out of pocket.
Manufacturing and Supply Chain Disruption
The company is expanding manufacturing capacity significantly to meet anticipated demand for obesity medicines. If manufacturing expansion is delayed or fails, or if suppliers cannot deliver materials reliably, the company could face product shortages that limit revenue. The company also depends on China-based suppliers for critical materials, creating vulnerability to tariffs and geopolitical tensions.
10-K Item 1A · Risk Factors
