Shares in Snapchat parent Snap Inc. tumbled today after pop star Rihanna ripped an ad on the platform for trivializing domestic abuse.

The company’s stock closed at $17.20, down nearly 4% for the day. It has experienced volatility lately after a new version of the social media platform met with customer protests.

The ad, for a game called Would You Rather, asked if people would “rather slap Rihanna or punch Chris Brown.” The singer was concerned that the ad, which has since been removed, sent a harmful message about domestic violence.

“Now SNAPCHAT I know you already know you ain’t my fav app out there! But I’m just trying to figure out what the point was with this mess! I’d love to call it ignorance, but I know you ain’t that dumb! You spent money to animate something that would intentionally bring shame to DV victims and made a joke of it!!!!,” Rihanna wrote in an Instagram post. “This isn’t about my personal feelings, cause I don’t have much of them…but all the women, children, and men that have been victims of DV in the past and especially the ones who haven’t made it out yet….you let us down! Shame on you. Throw the whole app-oligy away.”

Snap issued an apology, calling the ad “disgusting” and saying it should never have appeared on the service.

“We are so sorry we made the terrible mistake of allowing it through our review process,” Snap said in a statement to Deadline. “We are investigating how that happened so that we can make sure it never happens again.”

The ad, which was approved in error, violates Snap’s advertising guidelines — which explicitly forbid “shocking, sensational or disrespectful content.” The advertiser has been blocked from the platform.

Snap supports work to prevent domestic abuse, noting that Cindy Southworth, executive vice president of the National Network to End Domestic Violence, serves on its safety advisory board.

Last month, Snap’s stock took a beating after another celebrity, reality TV star Kylie Jenner, sent out a tweet suggesting she doesn’t use the app much anymore. That reinforced investor fears about the latest version of the app, sending the stock plummeting.