# Merck Stock Rises 71% Ahead of Keytruda Patent Cliff

> Merck's stock surged 71% as patent expiry looms for Keytruda, leaving little margin of safety.
- Title: Merck Stock Rises 71% Ahead of Keytruda Patent Cliff
- Summary: Merck's stock surged 71% as patent expiry looms for Keytruda, leaving little margin of safety. Merck's stock has risen 71% since last year as Keytruda's…
- Keywords: merck, keytruda, patent cliff, stock rally, biosimilar, medicare pricing, merck stock, keytruda patent, merck revenue, merck eps, money, business
- Source: Seekingalpha — https://seekingalpha.com/article/4956908-merck-a-71-percent-rally-leaves-little-margin-of-safety-ahead-of-keytrudas-patent-cliff
- Author: Vishal Jadaun
- Published: 2026-10-23T13:42:17+00:00
- Read time: 1 min
- Topics: merck, keytruda, patent cliff, stock rally, biosimilar, medicare pricing, merck stock, keytruda patent, merck revenue, merck eps, money, business
## Merck Stock Rally
Merck's stock has risen 71% over the last year, with shares trading about 7% above a $138 fair value estimate.
## Keytruda Patent Cliff
Keytruda remains over 50% of Merck's revenue, but biosimilar and Medicare pricing threats loom from 2029.
## Earnings Pressure
Core EPS declined ~6% in 2026 despite pipeline progress, with valuation reflecting re-rating optimism.
## Key takeaway

Merck's stock has risen 71% since last year as Keytruda's patent expires in 2029, limiting upside potential.