The fast-growing truckmaker, which in November completed the year’s biggest initial public offering, has hit a rough stretch recently, saying in December that it would fall “a few hundred vehicles short” of its goal to build 1,200 units for the year. Last week, the shares fell after Amazon.com Inc., a major investor and customer, said it would buy electric delivery vans from Stellantis NV.

Rivian said in a regulatory filing Monday that it produced 1,015 vehicles last year and delivered 920.

The stock fell 5.3% to $77.16 a share at 5:40 p.m. in New York after-hours trading, below its IPO price of $78. Through Monday’s close, Rivian’s shares had already fallen 21% this year.

The Wall Street Journal earlier reported the Copes departure.