Marseille owner Margarita Louis-Dreyfus has announced that she is planning to sell the club.
Dreyfus, 53, took charge after her husband Robert died of leukaemia in 2009 and Marseille went on to become French champions in 2010 as well as winning three Coupe de la Ligue crowns between 2010 and 2012.
Marseille made another push to win Ligue 1 last season under Marcelo Bielsa but, having capitulated on the pitch in the second half of the campaign, they lost several of their star players over the summer.
The southern club have struggled since the Argentine resigned in August and Dreyfus only decided to retain Bielsa's replacement Michel as manager until the end of the season following a crisis meeting this month.
However, angry fans once again called for Dreyfus and club president Vincent Labrune to leave after a 0-0 draw with Bordeaux on Sunday extended Marseille's winless home run in the league to 14 matches.
With the team only six points off the relegation zone, Dreyfus announced on Wednesday evening that she is hoping to attract new investment.
She said she had personally contributed millions of her own money over the years but that football had changed.
"Now it's states or specialist companies with virtually-unlimited capital that dominate," her statement on the Marseille website read.
Dreyfus also stated that one of her sons is seriously ill at the moment and that she regretted not being able to support the team and management in recent weeks as a result.
"I understand the frustration of not seeing OM being able to be competitive at this level and I inform you that I've taken the decision to yield the club to the best investor possible for the long term," her statement said.
"The price is not my main concern but on the other hand the ability of the new shareholder to construct a team that wins at the highest level is essential. I've asked my team of advisors to look after it."
Labrune also released a statement on Wednesday in which he praised the contribution that Dreyfus had made to the club.
"Since the death of Robert Louis-Dreyfus in 2009, Margarita's investment has been daily and unwavering," Labrune wrote.
"No one can realise her involvement. She always fulfilled her commitments.
"Her main desire today is to give new momentum to the club so that it can become more competitive. It's very good news for everyone who loves OM."
Former Marseille president Bernard ruled out a return on RMC, while Marseille native Eric Cantona also dismissed reports that he would be interested in becoming a sporting director as part of a new investment group.
"It's fiction," the ex-Marseille and Manchester United attacker told the C a vous programme on France 5. "Other investors would do a better job than me.
"I've put football behind me. It's been a while now - it's been 20 years. Marseille is my city. I love it but I've moved on from football."