Sanford made his fortune as the owner of First PREMIER Bank and PREMIER Bankcard, both among the nation's shadiest credit card providers. Premier Bankcard issues low-limit Mastercards and Visas to credit-impaired customers, charging higher-than-average interest rates and fees. The typical customer stays only 18 months before graduating to a better rate. "We provide a lifeline for credit-impaired people," Sanford told Forbes magazine. The Denny Sanford PREMIER Center in Sioux Falls, South Dakota, is named for him.
BusinessWeek magazine listed him as one of the top 50 most generous philanthropists in November, 2006.
On Saturday, February 3, 2007, Sanford announced a $400 million gift to Sioux Valley Hospitals and Health System, which renamed itself Sanford Health. Sanford's total philanthropic gifts have exceeded $500 million, and are generally geared toward improving the quality of life for children. Others receiving significant gifts include:
Children's Home Society of South Dakota, which cares for abused and neglected children.
Roundup River Ranch, an affiliate of Paul Newman's Association of Hole in the Wall Camps, located in Gypsum, CO, received $4 million -- $1 million in cash and $3 million as a matching gift.
Burnham Institute for Medical Research in La Jolla, CA and Orlando, FL received $50 million in January 2010, which was followed by a name change to Sanford-Burnham Medical Research Institute. This gift comes only 2 years after Sanford donated $20 million to a Sanford Center for Childhood Disease research at Burnham in La Jolla.
November 2013, University of California, San Diego announced a $100 million gift from Sanford for the creation of the Sanford Stem Cell Clinal Center at UCSD, the second largest donation in the university's history.
December 2013, Sanford pledged $10 million to the Crazy Horse Memorial, in South Dakota. The donation follows a $10 million matching pledge made by Sanford in 2007, along with a donation made by Huron couple, Paul and Donna Christen.
University of Minnesota
T. Denny graduated from the University of Minnesota in 1958 with a degree in psychology. In 2003, Sanford and the University of Minnesota announced that Sanford would donate $35 million towards a proposed new football stadium for the Minnesota Gophers football team; a deal which would have given him full naming rights. However, that deal fell through in late 2003 when the two parties were unable to reach an agreement on terms of the funding. Later in 2005, TCF Bank won the bid to receive naming rights for the new stadium.
On May 21, 2009, the University of Minnesota accepted a $6 million donation to name the athletic hall of fame within TCF Bank Stadium in his honor. This donation was the final amount to close out the $86 million in private fundraising for the stadium.