Complex sentence: On December 15,2006 Regan was fired from HarperCollins allegedly over anti-Semitic comments and the staff at ReganBooks reassigned within the HarperCollins General Book Group.
Split into simpler sentences: On December 15,2006 Regan was fired from HarperCollins, allegedly over anti-Semitic comments. The staff at ReganBooks were reassigned within the HarperCollins General Book Group.