Shares of Snap fell another 2 percent Friday, a day after Rihanna instructed her 60.9 million Instagram followers to delete the app.

It's the second time in a month an A-lister has done some serious damage to Snap's market capitalization. The stock plunged as much as 5 percent to session lows on Thursday following the pop star's post.

Earlier this week, Snapchat users began to notice an ad featuring 30-year-old pop icon Rihanna and her former boyfriend, Chris Brown, for the game, "Would You Rather?" The ad, which asks users to choose between slapping Rihanna or punching Chris Brown, seems to reference — and make light of — the couple's infamously abusive relationship.

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Although "Would You Rather," the mobile video game advertised, was not produced by Snap, the ad would have had to undergo and pass a review process before publishing. A Snap spokesperson said the majority of video advertising on Snapchat is purchased through a self-serve advertising platform, which is subject to review. Snap's advertising policy forbids "shocking, sensational, or disrespectful content."

Several days after screenshots of the controversial ad emerged, Rihanna broke her silence in a story on Snap's rival, Instagram.

"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!" she posted.

"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 [domestic violence] 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," she added.

Fans began to retweet her message, echoing her sentiment to delete Snapchat.

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The company's shares plunged as much as 5 percent, knocking $600 million off the market capitalization. Less than one month ago, Kylie Jenner took to Twitter to express her disdain for Snapchat's confusing redesign. Snap shares fell 7 percent.

Snap issued statements on both Monday and Thursday, apologizing for the ad that "was reviewed and approved in error."

"This advertisement is disgusting and never should have appeared on our service. We are so sorry we made the terrible mistake of allowing it through our review process. We are investigating how that happened so that we can make sure it never happens again," a Snap spokesperson wrote in an email.

Furthermore, Snap emphasized the ad was unaffiliated with Snapchat and that the company has since blocked the third party advertiser from its platform.

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Snap has largely remained on the sidelines as social media giants such as Facebook and Twitter increasingly struggle with quality control and content filtering. With Snap's revised business model and app redesign, which puts renewed emphasis on advertising, that may be changing.