Eli Lilly Stock Outperforms S&P 500 by 5x Over Decade as GLP-1 Boom Drives Valuation

Eli Lilly (NYSE: LLY) has seen its stock price surge more than 1,100% over the last ten years, vastly outperforming the S&P 500's 230% gain in the same period. This rally is primarily driven by the explosive growth of its GLP-1 diabetes and obesity medications, Mounjaro and Zepbound. However, a high price-to-earnings ratio and intensifying competition from rivals like Novo Nordisk are creating new risks for investors.

The Details

The financial ascent of Eli Lilly is anchored by the commercial success of its incretin analogs. In 2025, Mounjaro sales grew by 99% and Zepbound sales increased by 175%. Together, these two drugs generated $36.5 billion in 2025, accounting for approximately 56% of the company's total annual revenues. The company's Q4 2025 revenue reached $19.3 billion, marking a 43% year-over-year increase and beating Wall Street estimates by roughly 7%.

Despite this growth, the stock's valuation remains a point of contention. As of mid-April 2026, Eli Lilly's P/E ratio sits around 39x to 40x. While this is a drawdown from its five-year average of 56x, it remains significantly higher than the S&P 500 average of 26x and the broader drug stock average of 23x. Total returns over the decade, including reinvested dividends, are reported as high as 1,317.76%.

Competition in the GLP-1 space is accelerating. Novo Nordisk's oral GLP-1 pill, Wegovy, received FDA approval on December 22, 2025, and entered the U.S. market in January 2026. This presents a direct challenge to Lilly's dominance in the weight-loss sector. In response, Eli Lilly is developing its own oral option, orforglipron, with a U.S. launch expected in the second quarter of 2026.

Market share remains strong for now. Mounjaro currently leads in new prescriptions for type II diabetes incretin analogs globally, and Zepbound maintains approximately 70% of new branded obesity prescriptions. However, the stock has faced recent headwinds, declining approximately 13.6% year-to-date in 2026 following a strong 40.25% total return in 2025.

Context

The surge in Eli Lilly's valuation is mirrored by the massive potential of the global obesity drug market. Goldman Sachs estimates the market could reach nearly $95 billion by 2030 and potentially $125 billion by 2035. This projected growth has turned the obesity sector into a primary battlefield for pharmaceutical giants.

Beyond Novo Nordisk, other competitors are emerging. Pfizer and several smaller biotechnology firms, including Structure Therapeutics and Viking Therapeutics, are developing their own oral GLP-1 treatments, with phase III trials anticipated throughout 2026. This indicates a broader industry shift toward oral medications over traditional injectables.

Eli Lilly has also utilized its current revenue windfall to diversify. The company has been acquiring other firms with promising pipelines in various therapeutic areas to mitigate the risk of future patent cliffs. While these acquisitions expand their portfolio, the success of these new drug candidates remains uncertain.

What's Next

A critical catalyst for the industry is the anticipated expansion of Medicare access to obesity medicines, expected no later than July 2026. This move could significantly accelerate patient adoption and drive further revenue growth, although some Medicaid states have conversely begun reducing coverage.

Investors will be watching the Q2 2026 launch of orforglipron to see if Eli Lilly can maintain its lead in the shift toward oral GLP-1 delivery. The company's ability to manage its high valuation relative to its peers will depend on whether these new product launches and strategic acquisitions can justify a premium P/E ratio.

As the market matures, the focus will shift from initial adoption to long-term sustainability, particularly as competitors bring more affordable or convenient oral alternatives to market.