Longtime Tesla Inc (TSLA.O) executive Jerome Guillen, which oversaw the launch of its semi-electric trucks this year, has left the company, Tesla said on Monday, just three months after taking office.

Guillen, who has been with the company for more than a decade since he started as the Model S program director in 2010, oversaw the entire vehicle business of Tesla before being appointed chairman of the unit. Tesla Heavy Trucking in March. He was one of Tesla’s top four executives, including CEO Elon Musk.

Dan Levy, a Credit-Suisse analyst, said in a note that the start is “negative given that Guillen was previously seen as central to Tesla” because it was “arguably essential to stabilize the auto industry after the launch of the model 3 “in 2017.

Tesla has yet to start delivering its battery-powered semi-electric commercial truck, Musk has said in recent months that battery cell supply constraints could delay its mass production until 2022.

Musk also said in January that Tesla would be able to produce the Semi when its new 4680 cells could be produced in volume, which would alleviate a battery shortage.

Separately, Musk said on Sunday that Tesla had canceled its longer-range Model S Plaid +, which would use 4,680 cells and whose production had been postponed until next year.

“They made a big deal about the 4680… we’re just upset that the first (car with) 4680 was apparently abruptly canceled. It just raises more questions for them to answer,” said Louis Navellier, chief investment officer. at Navellier.

Tesla shares fell 0.7% after the market.

Guillen was one of the few longtime executives at Tesla who is known for the high turnover of their executives.

RJ Johnson, who ran Tesla Energy’s operations to sell solar and energy storage products, left the company after less than two years, according to his LinkedIn profile. He switched to Stealth Mode startup.

(This story corrects to remove the superfluous word “then” in paragraph 2, add a period)

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