Qatar has been a staunch supporter of Chief Executive Arnaud Lagardere even as some shareholders have assailed the chief executive's strategy for the company his father founded, which competes with Pearson and Bertelsmann AG in radio and book publishing.
A spokesman for the Qatar Investment Authority declined to comment.
Lagardere officials did not return a phone call seeking comment.
Lagardere, which also is a top shareholder in Airbus parent EADS, has struggled this year as the company's fledgling sports business has been plagued by integration problems.
The company was twice forced to scale back its annual core profit target, forcing its CEO to defend his decision to pour money into the venture.
Activist shareholder Guy Wyser-Pratte, who last year lost a battle to weaken Arnaud Lagardere's powers at the company, told Reuters that he expected Qatar to support the CEO as it has in the past.
"The Qataris are great friends of Arnaud Lagardere's father," Wyser-Pratte said.
"I think they're doing it to protect the son. They will undoubtedly support him whatever happens."
Lagardere officials could not be reached for comment on the remarks by Wyser-Pratte, who has been trying to challenge the outcome of an April 2010 shareholder vote rejecting two proposals he made aimed at greater oversight of the company's governance.
AMF said Qatar Holding now owned 13.2 million Lagardere shares, or 10.1 percent of its capital.
Qatar Holding is a unit of the Qatar Investment Authority, the emirate's sovereign wealth fund, which previously held 9.97 million shares, or 7.6 percent of Lagardere.
The move, which gives the investment vehicle a 7.9 percent voting rights stake, was carried out through off-market purchases, the regulator said.
Wyser-Pratte said he had taken a new stake in Lagardere after selling his previous holding after his 2010 defeat, but he declined to quantify the new stake.
Lagardere shares rose 2.5 percent to close at 20.24 euros, but they are still down 36 percent for the year.
Qatar earlier this year was reported to have considered investing in France's largest bank BNP Paribas.
In May another of the emirate's funds, Qatar Sports Investments, bought control of famed football club Paris Saint-Germain.
