Ikea’s flagship store in Stockholm is the largest of the furniture retailer’s 349 outlets, a blue and yellow behemoth that lures shoppers into its 55,200 square-meter (600,000 square feet) building that’s big enough to accommodate 10 football fields.

The shop’s size and bright color scheme stand in contrast to Ingvar Kamprad, the company’s founder and Sweden’s richest man, who rarely gives interviews and lives modestly, shunning the “fancy cars, posh titles, tailor-made uniforms or other status symbols,” that he criticized in his manifesto for Ikea written in 1976.

His three sons, Peter, Jonas and Mathias, inherited their father’s predilection for privacy -- they’ve never given an interview to the media -- and his stake in Ikano Group, a collection of financial, real estate and retail assets that has made them billionaires.

“They are extremely anonymous,” Stellan Bjork, co-author of Ikea Heading for the Future, a book on the retailer and Kamprad family, said in a phone interview. “I sometimes joke and say I wonder if they really exist.”

Established in 1988, Ikano represents a small piece of the Ikea group, which had revenue of 28.5 billion euros ($39.2 billion) in the year to Aug. 31, 2013. The company controls four Ikea stores in Southeast Asia, as well as $2.2 billion in property, an insurance unit and a credit-card business that processed $6.7 billion in transactions in 2012, according to the company’s website.

Malaysia, Singapore

The brothers, all of whom are in their 40s, have equal ownership of the closely held investment entity, according to a Jan. 30, 2014, e-mail from Marie Gallstad, Ikano’s head of communications. The company is valued at $3.3 billion, according to data compiled by Bloomberg. The siblings have never appeared individually as billionaires on an international wealth ranking.

Ikea, the world’s largest furniture retailer, is the biggest customer of Ikano’s credit-card business, which has more than 15 million active accounts, including customers of Goteborg, Sweden-based clothing retailer Lindex AB and Doncaster, England-based DFS Furniture Holdings Plc. The four Ikea stores Ikano controls in Malaysia, Singapore and Thailand attracted 17.4 million visitors and had revenue of 401 million euros in 2012, according to its website.

Ikano Ownership

“You have to separate Ikano from the other companies as it’s owned only by the sons,” Swedish journalist Bosse Vikingson, who has covered Ikea since 1987, said in a telephone interview. “Even so, it’s closely entwined with the rest of the group.”