The Arizona Diamondbacks (often shortened as the D-Backs) are an American professional baseball team based in Phoenix, Arizona. They play in the West Division of Major League Baseball's National League. Since the team's inception in 1998, the franchise has played home games at Chase Field, formerly known as Bank One Ballpark. The ballpark was renamed in 2005 as a result of Bank One Corporation's merger with JPMorgan Chase & Co. The Diamondbacks have won one World Series championship (in 2001), becoming the fastest expansion team in the major leagues to win a championship, doing it in only the fourth season since the franchise's inception in the 1998 Major League Baseball season.