system
A chat on subreddit /r/wallstreetbets
human
Pembrolizumab is the single defining factor of Merck right now. The entirety of stock movement is based around this single immunotherapy. 
  
 If pembrolizumab can consistently continue to show that it is a better PD-1 checkpoint inhibitor over competitors, which so far, it generally has managed to do, Merck will continue to do well.

gpt
Yea Keytruda is really important for them, but it's kind of disappointing that they don't have multiple irons in the fire currently.