Justina Vasquez Bloomberg

Snap Inc.'s flagship platform has lost some luster, at least according to one social-media influencer in the Kardashian-Jenner clan. The Snapchat parent's shares sank as much as 7.2 percent Thursday, wiping out $1.3 billion in market value, on the heels of a tweet from Kylie Jenner, who said she doesn't open the app anymore.

Snap Inc.'s flagship platform has lost some luster, at least according to one social-media influencer in the Kardashian-Jenner clan. The Snapchat parent's shares sank as much as 7.2 percent Thursday, wiping out $1.3 billion in market value, on the heels of a tweet from Kylie Jenner, who said she doesn't open the app anymore.