He is a prominent member of Sabean's baseball braintrust that has helped the Giants average 93 wins a season from 1997-2004, including winning the National League pennant in 2002 and division championships in 1997, 2000 and 2003. In addition to handling all Major League contract negotiations, his responsibilities include assisting Sabean in acquiring players via trade or free agency and building the Major League club, which in the last eight seasons has played only 11 games (of 1,296) while eliminated from post season contention. He is also responsible for overseeing waiver and rule compliance and managing the Major League payroll and budget.

Colletti, who has negotiated nearly 400 Major League contracts, has been responsible for signing such premier players as current and former Most Valuable Player Barry Bonds, along with All-Star and 2003 Cy Young Award runner-up Jason Schmidt and key players such as Ray Durham, Kirk Rueter, Marquis Grissom, Moises Alou, Omar Vizquel, Armando Benitez and Mike Matheny. Colletti works closely with Dick Tidrow in signing the organization's top picks in the annual First-Year Player Draft. During the last seven years, the Giants have signed 154 of the organization's top 166 selections, including all but one of the players selected in the first 10 rounds.

Prior to joining the Giants organization in 1994, Colletti worked for the Chicago Cubs, beginning his Major League Baseball career in 1982. He worked in both the media relations and baseball departments in Chicago, assisting in player contract negotiations, including those of Hall of Famer Ryne Sandberg and potential Hall of Famers Andre Dawson and Greg Maddux. In addition, he handled salary arbitration cases and assisted in player acquisitions. He was a key member of the organization when the Cubs won N.L. Eastern Division titles in 1984 and 1989. He was honored by Major League Baseball with the Robert O. Fishel Award for Public Relations Excellence in 1990.

The Chicago native graduated from Northern Illinois University and East Leyden High School in Franklin Park, IL, the same high school attended by Denver Broncos head coach Mike Shanahan, former Toronto Raptors general manager Glen Grunwald and former NBA head coach Jimmy Rodgers. He was inducted into the Triton College Sports Hall of Fame in 1993, entering the same time as former major league players Kirby Puckett, Lance Johnson and Jeff Reboulet. Ned and Gayle have two children, Lou and Jenna. Ned's brother Doug has been a member of the Chicago Bears' radio broadcast team for the past 19 seasons.

Colletti has assisted the Salesian Boys and Girls Club in San Francisco's North Beach neighborhood and has also assisted the Charlie Wedemeyer Family Outreach program which is committed to helping ALS patients and their families. The author of four books has been a guest speaker at many law firms as well as a guest lecturer to students who attend the law schools of Stanford University, the University of Michigan, the University of Illinois, DePaul University in Chicago and students from the School of Business at the University of Southern California.