This article is about the history of the Arizona Diamondbacks. The Diamondbacks (often shortened as the D-Backs), an American professional baseball team based in Phoenix, Arizona, were formed in 1998, based at Bank One Ballpark. This followed five years of preparation under the leadership of Jerry Colangelo. The Diamondbacks won the World Series championship in 2001, becoming the fastest expansion team in the Major Leagues to win a championship, doing so in only the fourth season since inception in 1998. Financial difficulties were then encountered and the home field was renamed to Chase Field in 2005, as a result of Bank One Corporation's merger with JPMorgan Chase & Co. After a lean period the team won the National League West division in 2011.