The revelation in Snap Inc.’s third-quarter earnings report sparked a sell-off in after-hours trading that could foreshadow one of the biggest one-day drops in the company’s stock since it went public in 2017.

Snap’s shares plunged by nearly 22% in Thursday’s extended trading. If that decrease is mirrored in Friday’s regular trading session, it will approach the stock’s previous one-day nadir in May 2018 when its price also plummeted by nearly 22%. A decline of that magnitude would wipe out nearly $30 billion in shareholder wealth.