Merck faces a looming financial crisis as it nears the 2028 expiration of patent protections for Keytruda, which currently accounts for half of its revenue. While the company reports a 4.9% revenue increase this quarter, its reliance on Keytruda places it as the most exposed major player to upcoming patent cliffs, with industry-wide revenue losses expected to exceed $300 billion. This contrasts sharply with competitors like Eli Lilly, who are demonstrating strong growth despite the challenging landscape.