Eli Lilly's stock is making new highs driven by two catalysts: Medicare's decision to include GLP-1 weight-loss drugs (like Mounjaro and Zepbound) in its coverage framework, and a fiscal year revenue print of $65.2B — a 44.7% year-over-year surge. Net margins came in at 31.7% with diluted EPS of $22.95, reflecting genuine operating leverage as the GLP-1 franchise scales.

The Medicare inclusion is the structural catalyst that changes the total addressable market calculus. Previously, GLP-1 obesity drugs were largely excluded from Medicare Part D, limiting access for tens of millions of seniors. Broad inclusion dramatically expands the paying patient pool for Zepbound, putting pressure on rival Novo Nordisk's Ozempic/Wegovy franchise and opening a multi-year volume story for LLY.

The bull case rests on the intersection of explosive revenue growth, margin expansion headroom, and a regulatory tailwind that's genuinely incremental — not priced in until recently. At ~31.7% net margins on a $65B revenue base growing nearly 45%, the earnings power trajectory is hard to dismiss.

The bear case is that at new highs following a major re-rating, LLY already reflects a significant portion of the GLP-1 opportunity. Valuation multiples are elevated, the Medicare coverage timeline and reimbursement rates could compress pricing power, and any manufacturing capacity constraints or competitive erosion from pipeline entrants (Roche, Viking Therapeutics, Amgen) could slow the growth narrative faster than consensus expects.

Key watchpoints: Medicare reimbursement rate details, Zepbound volume trajectory in next quarterly print, and any pipeline readouts from GLP-1 competitors. The stock is at highs, so the near-term risk/reward is asymmetric depending on whether execution stays flawless.