Rolling Stone’s covers minted stars. In its pages, Mr. Wenner cultivated literary icons, including Hunter S. Thompson and Tom Wolfe, whose lengthy articles chronicled an often chaotic and intoxicating world. It was at Rolling Stone where the celebrity photographer Annie Leibovitz got her start.

With the magazine, Mr. Wenner seized the freewheeling culture of the 1960s and 1970s and spun it into a publication that some of the baby boomer ilk came to call “The Bible.” It covered music, but also pop culture, entertainment and politics.

Jann Wenner started other magazines, including Outside in 1977 and Family Life in 1993. His name, however, was synonymous with Rolling Stone.

Mr. Wenner rocketed into the celebrity world that had long enchanted him. He partied with rock stars and toured the world on his private jet. In the mid-1990s, an affair Mr. Wenner was having with a young male fashion designer catapulted him into the gossip pages alongside some of his subjects.

Still, Mr. Wenner’s critics, especially in recent years, accused him of publishing a staid magazine that failed to recognize emerging artists and musical styles. Advertisers who once flocked to Rolling Stone’s pages began turning away. More recently, Mr. Wenner has suffered a heart attack and a broken hip that left him walking with a cane. At a swanky party in October for an HBO documentary about Rolling Stone — while guests nibbled on sushi and a DJ played classic rock — Mr. Wenner ambled over to his table at the beginning of the night and greeted guests from his seat.

And if the magazine industry has not been kind over the last decade, it has been particularly brutal for small publishers. Wenner Media — and Rolling Stone — has done itself no favors: A botched article in late 2014 about an alleged gang rape at the University of Virginia damaged the magazine’s reputation at the same time it was trying to combat steepening declines in print advertising and circulation.

When Wenner Media said in September that it was exploring a sale of its remaining 51 percent stake in Rolling Stone, both Gus and Jann Wenner said they expected a range of interested parties. Gus Wenner had been particularly optimistic that a technology company would buy the magazine.

Penske Media, which was founded in 2003 and has headquarters in Los Angeles and New York, the investment in Wenner Media actually underscores how perilous the magazine industry has become. Rolling Stone used to be worth much more; Mr. Wenner once boasted he had turned down a $500 million offer for the magazine. In a release announcing the deal, Penske Media and Wenner Media cited Penske’s expertise in digital media and live events as attributes that would benefit Rolling Stone.