Shares of Irvine-based Rivian Automotive declined after the electric-vehicle maker said it will recall about 13,000 vehicles it delivered to customers after discovering a minor structural defect.

The stock fell 8.5% at 9:37 a.m. Monday in New York, deepening a slide that had already wiped out two-thirds of its value this year through Friday’s close.Irvine, California-based Rivian is making the recall because a fastener “may not have been sufficiently torqued,” Chief Executive Officer RJ Scaringe said in a letter to customers that was seen by Bloomberg News. The nut could loosen fully in “rare circumstances,” he added.

The company said it’s recalling almost all of the vehicles delivered to customers even though the issue was discovered only in seven, “out of an abundance of caution.” Rivian said it isn’t aware of any injuries resulting from the issue.

The cost of the recall isn’t material, according to a person familiar with the matter.

The recall is a setback for Rivian, which has only recently overcome production problems and parts shortages to deliver its EVs to customers in meaningful volumes. The company also had to deal with the fallout of an embarrassing U-turn in March to raise prices on pre-orders.

Free adjustments

Rivian builds the battery-electric R1T pickup and R1S sport utility vehicle for consumers. It also has a deal with Inc., one of its biggest shareholders, to build 100,000 EV delivery vans by the end of this decade.

“The safety of our customers will always be our top priority, and we are committed to fixing this issue on any affected vehicles as quickly as possible,” a Rivian spokesperson said in a statement. “We will make any necessary adjustments free of charge at one of our service centers.”

Most customers will be able to get their vehicles fixed within minutes, Scaringe said in the letter, by tightening the fastener to a higher torque tolerance. A small percentage of vehicles may need to have parts replaced.

Rivian was seen as the hottest new EV startup to challenge incumbent Tesla Inc., after a monster initial public offering in November and big-name Wall Street backers and strategic investors like Ford Motor Co. However, production challenges have sent the shares down this year, though its reaffirmation of a goal of building 25,000 EVs this year helped trim losses.