PHOENIX -- University of Phoenix founder Dr. John Sperling died Friday at the age of 93 at a hospital in the San Francisco area, according to the Apollo Education Group's website.
No cause of death was given.
Businessweek says Sperling battled founded UOP in the 1970s and battled for its accreditation and respect.
Through Apollo, the Phoenix-based publicly traded parent of University of Phoenix, Sperling became a billionaire. Forbes magazine estimated that his net worth peaked at $1.7 billion in 2005 before declining to $1.2 billion in 2012 and less than $1 billion in 2013, as his unorthodox, decentralized university faced renewed scrutiny of its finances and efficacy.
"Dr. Sperling's indomitable ideas and life's work served as a catalyst for innovations widely accepted as having made higher education more accessible to adult students," the founder's son, Peter, said in a statement. "As we said last year in a ceremony held in his honor: John Sperling never backed down from a fight. As a boy, he fought sickness and poverty ... Finally, when he founded University of Phoenix, John Sperling challenged anyone who tried to stop him."
UOP has more than 100 locations around the U.S. and is one of the country's biggest for-profit colleges. Its student population peaked at 470,800 in 2010 but declined to just over 300,000 in early 2013.
The Apollo group said in 2012 it would be closing several campuses and smaller centers. Peter Sperling became chairman of the company late that year.