Smelling blood, the activist investor Elliott Investment Management took a 3.1 per cent stake in UDG Healthcare this week. Elliott has a tough reputation. The Elliott playbook is to find companies that aren’t doing everything possible to maximise returns for shareholders, buy a stake in them, and agitate for change. What has attracted Elliott to UDG is the offer for the company by the august New York private equity fund, Clayton, Dubilier & Rice (CD&R). CD&R offered to buy UDG for an enterprise value of €3.2 billion. That’s a premium of 21.5 per cent over the market value, and a…