Key Points Sales of blockbuster drug Keytruda missed expectations. The drug's patents will begin to expire in 2028. Merck also lowered revenue guidance for 2025. 10 stocks we like better than Merck › The stock for pharmaceutical giant Merck (NYSE: MRK) was trading down more than 3% Monday morning. That's a big drop in just a few hours to start the week. So, what's going on? It might have to do with the fact that last week the New Jersey-based drugmaker released third-quarter results. Investors ...