Starboard buys into drugmaker Perrigo and pushes for changes

Activist investor Starboard Value says it bought a 4.6 percent stake in Perrigo and is pushing the Irish drugmaker to shake up its business.

In a letter to Perrigo's management, Starboard says that the company's performance has been "poor" and that it needs to make changes to create value for shareholders. Shares of Perrigo Co. are down more than 49 percent in the last year.

Starboard says Perrigo shares have fallen sharply since it rejected a takeover bid from rival Mylan NV last year and that its plans to improve the company on its own did not pan out.

In a statement Monday, Perrigo says that it is reviewing Starboard's letter carefully.

Perrigo shares rose $5.41, or 6.1 percent, to $94.12 in midday trading Monday.