There has been a board shakeup at Chipotle, and Bill Ackman is happy about it

Chipotle has named four new people to its 12-person board of directors, including two people who work with the activist firm Pershing Square Capital, which took a stake in the company earlier this year.

The appointments are Paul T. Cappuccio, Robin S. Hickenlooper, Ali Namvar and Matthew Paull.

Namvar is a partner at Pershing Square, and has worked there since 2006, according to a Chipotle press statement. Paull currently sits on the Pershing Square's advisory board.

Cappuccio is Time Warner's executive vice president and general counsel, and Hicklooper is the senior vice president of corporate development at Liberty Global.

"We are pleased that Chipotle has taken the important step of refreshing its Board which will position the company for continued growth and long-term success," Bill Ackman, founder of hedge fund Pershing Square, said in the statement.

Ackman's $11 billion Pershing Square took a 9.9% stake in Chipotle in September. The firm's performance has dropped since last year. Pershing Square Holdings, a proxy for the firm's flagship hedge fund, is down about 12% through December 13.