A hedge fund run by a famed investor said Tuesday it has taken a large stake in Amgen and now wants the biotech drugmaker to consider splitting up into two.

In a letter to investors, Third Point, a hedge fund run by Daniel Loeb, said it has recently increased its stake by an unspecified amount, making it one of the drugmaker’s top shareholders. According to FactSet, Third Point already owned about 450,000 Amgen shares, a stake worth roughly $64.8 million.

In response, Amgen said that its board and management are continually assessing the company’s business.

Third Point said Amgen Inc., which makes a range of drugs for arthritis, anemia and other diseases, is not given enough credit for its existing drugs or the potential of its pipeline. It believes that the stock can reach $218 by the end of 2016 — up 51 percent from Tuesday’s close — if Amgen focused on research and development and trimmed expenses. Should the company pursue its suggestion to breaking up into two companies, Third Point said it believes that the total value would be nearly $249 per share.

Amgen, based in Thousand Oaks, California, said it will update investors about its restructuring when it reports results next week. In its last quarterly report it announced it would lay off up to 15 percent of its workforce and shut four sites.

Shares of Amgen are up about 26 percent in the year to date, versus a 5 percent gain in the benchmark S&P 500 index.