Pfizer's business model is a research-intensive pharmaceutical enterprise built on the discovery, development, manufacturing, and commercialization of prescription medicines and vaccines. The model is capital-intensive at every stage — R&D investment to generate the drug candidates, clinical trial investment to prove efficacy and safety, manufacturing infrastructure to produce at scale, and commercial infrastructure to market and distribute globally — and requires sustained blockbuster revenue to fund the research pipeline that generates the next cycle of products. The revenue model centers on patent-protected branded pharmaceuticals that command premium pricing during their exclusivity period — typically 10–15 years from patent grant, though effective market exclusivity (accounting for development time before approval) averages 7–12 years. During this window, Pfizer earns pricing power that reflects both the clinical value of the drug and the absence of generic competition. After patent expiry, generic manufacturers can produce chemical equivalents at a fraction of the brand price, typically reducing the originator's market share to 10–20% within 12 months of generic entry. This cliff dynamic — high revenue during exclusivity, steep decline at expiry — drives the pharmaceutical industry's perpetual need for pipeline replenishment. Pfizer's commercial organization is structured around five therapeutic areas that represent the company's primary revenue drivers: Oncology (cancer medicines, the fastest-growing and highest-margin segment), Vaccines (Prevnar pneumococcal vaccines, Comirnaty COVID vaccine, and the expanding RSV and flu vaccine pipeline), Internal Medicine (cardiovascular, metabolic, and rare disease medicines), Hospital (sterile injectable anti-infectives and biologics for hospital use), and Inflammation and Immunology (biologics for autoimmune conditions). This therapeutic area structure guides both R&D investment allocation and commercial resource deployment. The oncology segment has become Pfizer's strategic center of gravity following the $43 billion Seagen acquisition completed in 2023. Seagen brought a portfolio of four approved antibody-drug conjugate (ADC) cancer medicines — Adcetris, Padcev, Tukysa, and Tivdak — and a pipeline of additional ADC candidates. ADCs are a class of precision oncology drugs that combine the targeting specificity of monoclonal antibodies with the cell-killing potency of cytotoxic chemotherapy agents, delivering cancer-killing payload specifically to tumor cells while sparing healthy tissue. This mechanism represents a genuine therapeutic advance over traditional chemotherapy and has generated strong clinical results across multiple cancer types. Pfizer's bet on ADCs through the Seagen acquisition is a conviction play that this class will define the next decade of oncology treatment — a conviction shared by nearly every other major pharmaceutical company, making the competitive dynamics in ADC development intense. The vaccine business model has been transformed by the COVID experience. Prevnar 13 and Prevnar 20 — pneumococcal conjugate vaccines — have been the foundation of Pfizer's vaccine revenue for 15 years, generating $5–6 billion annually at peak through pediatric and adult immunization programs globally. The COVID vaccine partnership with BioNTech introduced a radically different economics structure: Pfizer and BioNTech share profits on Comirnaty approximately equally, meaning that despite being the largest-revenue vaccine in history, Pfizer retained only approximately 50% of the gross margin. The mRNA platform, now proven at massive scale, provides a template for accelerated vaccine development across influenza, RSV, and other respiratory diseases — markets where Pfizer is now investing aggressively. Manufacturing is a core competitive differentiator and a significant capital requirement. Pfizer operates approximately 40 manufacturing sites globally, producing everything from small-molecule APIs and finished dose forms to complex biologics and mRNA vaccines. The ability to scale mRNA vaccine production from zero to over 3 billion doses in 2021 — drawing on the existing sterile fill-finish manufacturing infrastructure built for other injectable products — was a decisive advantage in the COVID vaccine program. This manufacturing depth, combined with global cold chain distribution capability, is a genuine barrier to entry for smaller competitors. The pricing model for branded pharmaceuticals in the United States — the world's most profitable pharmaceutical market, contributing approximately 40–45% of Pfizer's global revenue — operates under managed care and pharmacy benefit manager (PBM) contracting that significantly complicates simple list price analysis. While Pfizer's list prices for major drugs are often criticized as excessive, net realized prices after rebates, discounts, and co-pay assistance typically represent 50–70% of list price in major therapeutic categories. The US political environment around drug pricing — most recently the Inflation Reduction Act's Medicare drug price negotiation provisions — represents a structural shift in the pricing environment that will affect Pfizer's long-term US revenue trajectory.