The death of billionaire Liliane Bettencourt focused attention on Friday on how L'Oreal's founding family and major shareholder Nestle would manage their stakes in the world's biggest cosmetics firm.
Bettencourt, listed by Forbes as the world's richest woman and heiress to the company started by her father, died at the age of 94, relatives said late on Thursday.
Bettencourt's family owns 33 percent of L'Oreal. Relatives including her daughter have managed the stake for several years since a court found she was suffering from a form of dementia.
Nestle retains a 23 percent stake in the company.
The death of the matriarch signals a potential shift in L'Oreal's ownership. A 43-year-old agreement between the family and Nestle not to increase their stakes will expire after six months. There were no restrictions on reducing the stakes.
"Speculation will now inevitably be re-ignited around Nestle's intentions towards its L'Oreal stake," analysts at Jefferies said.
"This holds out the prospect of L'Oreal either buying in the stake, or perhaps even Nestle buying L'Oreal outright."
Hopes of change lifted L'Oreal's shares 3 percent, making it the best performer on France's benchmark CAC-40 index.
Bettencourt's only daughter Françoise Bettencourt-Meyers, who sits on L'Oreal's board with her husband and one son, has said the family remained committed to L'Oreal and its management.
"While the Bettencourt family has reasserted its commitment to the group, Nestle's position is more in doubt," said Gregoire Laverne, fund manager at Roche-Brune.