Rihanna wiped around US$600m off Snapchat's parent company on Thursday when she criticised the messaging app for hosting an advert that appeared to make light of her history as a victim of domestic violence.
Shares in Snap Inc fell almost 5pc as the popstar criticised the app on Instagram, Snapchat's main rival.
"Now SNAPCHAT I know you already know you ain't my fav app out there!" Rihanna said "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!"
The singer was responding to an advert on the social media app asking users if they would rather "slap Rihanna or punch Chris Brown". Brown was convicted of assaulting Rihanna in 2009 when the two were in a relationship.
The incident was the latest example of celebrities' apparent ability to affect Snap's share price. Last month Kylie Jenner sent the company's share price tumbling when she said: "sooo does anyone else not open Snapchat anymore? Or is it just me... ugh this is so sad."
Snap apologised for the advert on Thursday.
"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," the company said.
The advert, which promoted a mobile game called Would You Rather, was deleted along with the advertiser itself.
Rihanna appeared to urge her fans to delete Snapchat, which is popular among teenagers and young adults.
"You spent money to animate something that would intentionally bring shame to DV [domestic violence] victims and made a joke of it!!" she wrote
"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."