Two people founded Regeneron Pharmaceuticals in 1988 and both of them still run it. Leonard Schleifer, the physician-scientist CEO, and George Yancopoulos, the chief scientific officer, have operated as co-leadership for 37 years — making Regeneron the only company in the $66 billion market cap range in biotechnology that has never changed its founding leadership. That continuity has produced a research culture that invented EYLEA for wet AMD in 2011, Dupixent for atopic dermatitis in 2017, and a pipeline of 50 product candidates including 18 in late-stage development. The company generated $14.3 billion in total revenue in fiscal year 2025 and employs more than 15,400 people across 12 countries. But the operating mechanics are more concentrated than those headline numbers suggest. Two wholesale customers — Besse Medical, a subsidiary of Cencora, and McKesson Corporation — collectively accounted for 74 percent of gross product revenue in 2024. That distribution concentration means a single inventory adjustment cycle at either company can swing quarterly reported revenue by hundreds of millions of dollars. Dupixent is the central commercial story: a biologic antibody that treats atopic dermatitis, asthma, and five other indications with a safety profile that avoids the immunosuppression risks associated with systemic corticosteroids and JAK inhibitors. The drug is co-commercialized with Sanofi under a 2007 collaboration agreement, which means Regeneron's reported Dupixent economics include profit-sharing calculations — a $603.7 million contingent reimbursement obligation to Sanofi reduced reported collaboration profit in 2024 alone. The Regeneron Genetics Center is the company's long-term structural advantage. It creates a closed-loop system where human genetic discoveries flow directly into preclinical validation and then into clinical development, reducing the randomness of drug discovery without the brute-force approach of large pharma acquisition strategies. $5.9 billion invested in R&D in 2025 — 41 percent of total revenue — funds that pipeline, a ratio that exceeds every large-cap pharmaceutical peer.