The decision was made at the "very highest levels" at Citi, a source told Sports Business Daily, and leaves the bank category for Team USA vacant for the first time since 2011.

Citi has partnered the USOC at the past three Olympic Games - London 2012, Sochi 2014 and Rio 2016.

It had been one of Team USA’s most active sponsors in the Rio 2016 cycle, signing high-profile athletes such as beach volleyball player Kerri Walsh Jennings and sprinter Allyson Felix to head its campaign and buying advertising exclusivity with television broadcasting company NBC during the Games.

One reason behind Citi’s decision, a source told Sports Business Daily, was frustration over how rival banks can use the Games by accessing Worldwide Olympic Partner Visa’s pass-through rights in the payment card category.

"We have great respect for the Olympic Movement and the values it represents," Mark Costiglio, Citi’s head of financial communications, said in a statement.

"We were proud to partner with the United States Olympic Committee for the last three Games and wish them the greatest success going forward."

Renewal talks between Citi and the USOC recently broke down, reports claim.

"Citi leaves a strong legacy of promoting Team USA and engaging the public in support of America’s Olympic and Paralympic athletes," Mitch Poll, the USOC’s senior vice-president and marketing director, said.

"They were a very active supporter of Team USA and member of the great family of Team USA partners, and we wish them the best moving forward."

Experts say the value of an Olympics sponsorship, which is gradually growing in cost, may not be what it once was in the past.

"People are spending five, six, or 10 times the value to be an official sponsor when someone can spend a couple hundred thousand and run a commercial - the average viewer might not know the difference," said Roger Payne, director of research and analytics at Dallas-based The Marketing Arm, told Advertising Age.

"It comes down to the value proposition."

In 2011, Citi became the first financial brand to sponsor the Olympic Games since Bank of America's sponsorship ended two years earlier.

The financial services company donated $500,000 (£405,000/€482,00) to the USOC’s "Every Step of the Way" programme, aimed at developing the nation's next generation of athletes, in 2013 - the same year in which it renewed the Olympics sponsorship for a four-year cycle. 

Citi follows telecommunications company AT&T, Hilton Hotels and Resorts and luxury vehicles company BMW in leaving the USOC programme after Rio 2016.

Comcast and Toyota have replaced AT&T and BMW respectively, while the hotel category remains open.

Last week, USOC chief executive Scott Blackmun predicted a "significant increase" in overall sponsorship revenue for the upcoming four-year Olympic cycle.

"I would say we had an excellent year, and we have excellent prospects," he said.

"We do have a handful of categories we need to fill because of decisions by some sponsors not to renew, but the truth is both the [International Olympic Committee’s] The Olympic Partner programme and our domestic programme are healthy."