Chipotle Mexican Grill (NYSE: CMG ) continues to change its structure. On Dec. 12, the company announced that it would no longer use the dual CEO structure that had been in place for years, making founder Steve Ells the sole person in that role. Two days later, four people – Ali Namvar, Matthew Paull, Robin Hickenlooper and Paul Cappuccio – were added to Chipotle's board of directors, which now consists of 12 members. The new members have terms that will initially take them through the company's annual shareholder meeting, which is expected to take place in the spring. Ellis said, that this move, gives us the oversight, accountability and leadership we need as we continue our efforts to re-establish Chipotle as the leader we have been for much of our history. This decision was made partly in response to Pershing Square (NYSE: SQ ) purchasing a 9.9 percent stake in Chipotle three months earlier. Two of the four new members – Namvar and Paull – are affiliated with that hedge fund management company.