Snap Inc. shares finished lower Thursday after the singer Rihanna spoke out against a controversial Snapchat ad and appeared to encourage people to delete the app.

Snap SNAP, +0.32% shares closed down 3.6% at $17.20 Thursday, hitting an intraday low of $16.91, after Rihanna called the company out in an Instagram post that was widely shared and cross-posted to other social networks, including Twitter TWTR, -0.42% .

Snap shares are down 13% for the month but are still up nearly 18% for the year. In comparison, Facebook FB, +0.37% is up 3.1% this month, and 4.2% year-to-date, while Twitter is up more than 12% on the month, and 49% on the year. The Dow Jones Industrial Average DJIA, +0.14% has gained 0.6% on the year, and the S&P 500 SPX, +0.38% is up 2.8%.

Earlier in the week, Snap apologized for running the mobile video-game ad for “Would You Rather,” which welcomed users to either “Slap Rihanna” or “Punch Chris Brown,” an obvious reference to a 2009 incident when the two were dating that resulted in Brown being charged with felony assault.

Here’s the offending ad and Rihanna’s response in one tweet:

In the age of social media, companies are learning that if you live by celebrity endorsement, you can also die by it. Snap investors learned this the hard way earlier in the year when shares tanked following a Kylie Jenner tweet criticizing the redesign of the app.

In her post, Rihanna both refers to the Snap apology and seems to urge people to delete the app by saying, “Throw the whole app-oligy away.”

On Thursday, Snap addressed the ad with the following statement:

“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.”

Rihanna’s post drew widespread reaction Thursday, with some fans appearing to have deleted the app: