Bill Ackman's Pershing Square Accumulates 11.3% Stake in Ceridian (CEN)

In a 13G (passive stake) filing on Ceridian Corporation (NYSE: CEN) this morning, activist investor Bill Ackman's Pershing Square Capital hedge fund disclosed an 11.3% stake (15.7 million shares) in the company. The firm did not disclose a position in Ceridian for the quarter ended September 30, 2006.

Ackman may be best known for his fight to implement changes at McDonald's Corp. (NYSE: MCD). He was also instrumental in getting Wendy's International (NYSE: WEN) to make aggressive changes, including spinning off its Tim Horton's (NYSE: THI) chain.

Recently, Ackman has built large stakes in book retailers Borders Group Inc. (NYSE: BGP) and Barnes & Noble (NYSE: BKS) - calling both companies undervalued.

Ceridian is a top human resources outsourcing company.

NOTE: 13G filings at the main premium site are open to the public. You can view them here: http://www.streetinsider.com/13Gs