SAN FRANCISCO – Investors are throwing Snap shares overboard after the owner Snapchat reported slower than expected user growth.

Wall Street saw Snap shares tumble by as much as 20 percent, amid concerns that the photo-messaging app is being beaten by established rivals such as Facebook’s Instagram.

The number of Snap daily active users rose to 178 million in Q3 from 173 million in Q2, but remained well below the 181.8 million expected by analysts.