The move comes after Sports Illustrated's L. Jon Wertheim and Viv Bernstein reported Richardson had paid out settlements to resolve allegations he acted inappropriately at the workplace.
According to Wertheim and Bernstein, Richardson allegedly made inappropriate comments toward women, particularly on "Jeans Day" at the team's offices.
In other instances, Richardson is said to have performed "back rubs that lingered too long or went too low down the spine" or attempted to buckle the seat belt of female passengers, which would allow him to "[brush] his hand across their breasts before putting the belt in the clasp."
Richardson also allegedly used a racial slur when speaking to an African-American scout for the Panthers. The scout subsequently received a confidential settlement and left the team.
In his statement announcing his plan to sell the Panthers, Richardson didn't reference the allegations against him:
"I believe that it is time to turn the franchise over to new ownership. Therefore, I will put the team up for sale at the conclusion of this NFL season. We will not begin the sale process, nor will we entertain any inquiries, until the very last game is played. I hope everyone in this organization, both on and off the field, will be firmly focused on just one mission: to play and win the Super Bowl."
Forbes valued the Panthers at $2.3 billion in September, making Carolina the 21st-most expensive team in the NFL.