Is Merck & Co. Stock a Buy?

Over the past five years, shares of Merck & Co. (NYSE: MRK) are up by about 40.5%. While that isn't a bad performance, it trails that of the S&P 500 -- which is up by 60.3% -- over the same period. Further, Merck's stock isn't exactly cheap when accounting for future earnings. The company's price-to-earnings-growth (PEG) ratio is currently 1.70.

Given these metrics, Merck doesn't seem like a screaming buy, but there's much more to the company than its performance over the past five years and its PEG ratio. With that in mind, let's dig a little deeper and find out whether it's worth buying shares of this pharma giant today.

The single best argument for why you should buy shares of Merck is none other than Keytruda. This drug is approved for a long list of cancers, including head and neck cancer, lung cancer, melanoma, and lymphoma. Keytruda continues to generate growing sales. During the fourth quarter, sales of the blockbuster cancer drug were $3.1 billion, a 45% increase year over year.

Source Fool.com