Rivian gave a mixed outlook late Thursday after beating fourth quarter expectations. Rivian stock slid on Friday but found support at a key level. The upstart Tesla rival also delivered its first gross quarterly profit.

Startup Rivian Automotive hit a milestone Thursday, reporting its first quarter of gross profit. The hitch: Much of it was driven by sales of regulatory credits to other automakers, rather than electric-vehicle sales.

Rivian Automotive Inc. makes good on its promise to get to its first quarterly gross profit and blows past Wall Street estimates for its sales.