LOS ANGELES, United States — Guess? Inc. shares plummeted after Kate Upton accused co-founder Paul Marciano of sexual harassment, embroiling the fashion brand in the #MeToo movement.

Upton, a supermodel and actress, said on social media Wednesday that Marciano “shouldn’t be allowed to use his power in the industry to sexually and emotionally harass women.” She added the #MeToo hashtag, which has become a rallying cry for the movement against sexual assault and workplace misconduct.

Marciano stepped down as chief executive officer of Guess in 2015 but still has major influence in the company in his roles as chairman at chief creative officer. He art-directed the latest advertising campaign for Guess, featuring Jennifer Lopez, and appeared at a party celebrating its launch on Wednesday night.

“I’m disappointed that such an iconic women’s brand @Guess is still empowering Paul Marciano as their creative director,” Upton said in a tweet.

Guess suffered its worst stock decline in more than two months in the wake of the accusation, sending its shares down as much as 12 percent to $16.16. They had gained nearly 40 percent last year.

Marciano held more than 14 percent of Guess shares as of March 2017, according to data compiled by Bloomberg. That stake would be worth roughly $25 million less after Thursday’s decline.

The Los Angeles-based company didn’t immediately respond to a request for comment.

Upton also spoke briefly with TMZ as she walked through Los Angeles International Airport on Wednesday night. “I’m excited to tell my whole story,” she said.

By Kim Bhasin; editor: Nick Turner