Loeb remains relatively bullish on the American economy
The letter added that a more radical but viable option would be to split the company in two.
"Given the diverse nature of its assets–cash‐generative Mature Products and R&D‐intensive Growth Products–we believe that Amgen could benefit from a separation into distinct operating units with separate financial statements and should seriously consider separating into two companies," the letter said.
A spokesman for Third Point didn't immediately respond to a request for comment.
Amgen said it appreciated Loeb's comments, but did not discuss specifics.
"Amgen has always appreciated the perspectives of all of its shareholders, including Third Point, and welcomes constructive input toward our common goal of enhancing shareholder value," the company said in a statement.
The Third Point letter also said the fund is long eBay and Alibaba. It also exited its equity investment in Sony.
Third Point's Offshore fund is up 6 percent in 2014 through September. Loeb remains relatively bullish on the American economy despite market turmoil in early October.