Is Pfizer Stock the Biggest Bargain in the S&P 500?

When something seems too good to be true it might not be.Pfizer (PFE 0.08%) stock is relatively cheap. I can easily back up that claim. The big drugmaker's shares trade at lower forward earnings multiples than the S&P 500 and the S&P 500 healthcare sector. That meets the definition of relatively cheap.However, I wouldn't go so far as to claim that Pfizer is the cheapest stock in the S&P 500. At least, I wouldn't have until I saw something recently that blew me away and prompted me to wonder if Pfizer just m ...