Yankees' Andy Pettitte to retire after seasonAuthor:SI StaffPublish date:Sep 20, 2013Yankees left-handed pitcher Andy Pettitte announced he will retire at the end of the season. Chris Carlson/AP He joined old buddies Rivera, Derek Jeter and Jorge Posada to make up the "Core Four'' that has led the Yankees to more than a decade and a half of sustained success. Copyright 2014 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.