Originally Published: 04 AUG 23 15:33 ET

Updated: 04 AUG 23 16:07 ET

By Peter Valdes-Dapena, CNN

New York (CNN) — The president and chief executive of Nikola, the Arizona-based electric and hydrogen semi truck manufacturer, is leaving the company effective immediately, the company announced Friday.

Michael Lohscheller is leaving the company so that he can return to Europe to focus on a family health emergency, the company said. He will be replaced in the CEO role by Stephen Girsky, a former General Motors executive who had been chairman of the board. Girsky will retain a board seat, but give up the chairman role as he transitions to CEO, effective immediately. Lohscheller’s predecessor, Mark Russell, also stayed in the CEO role for less than 18 months, meaning Girsky is the company’s fourth CEO in as many years.

The company has had a rocky start since it was founded in 2015 by its former chairman Trevor Milton, who left the company in 2021. Not long after leaving the company under acccusations of misleading investors, Milton was arrested and later convicted of fraud. Prosecutors said Milton had misled investors about how far along the company was in developing its hydrogen- and battery-powered electric semi trucks. Milton still maintains a roughly 8% ownership stake in Nikola.

Since then the company has started building and delivering trucks to customers. So far this year, the company has built 96 trucks and shipped 76 battery electric vehicles, according to earnings that were also announced Friday. Nikola reported a net loss of $387 million in the first half of the year, up from $326 million in the first half of last year. The company’s loss from continuing operations was down compared to last year, though.

Nikola’s shares fell 26% at Friday’s market closing on the news.

Lohscheller hadn’t been CEO very long. He became president of Nikola in March 2022, and took over the CEO role in November of last year. During his time as president and CEO, Nikola focused its business more tightly on the US market.

In his career, Lohscheller has had executive roles at various major automakers, including Volkswagen Group, where he was head of Volkswagen USA. Before joining Nikola, Loscheller had, for less than a year, been CEO of the Vietnamese automaker VinFast, which recently began selling electric SUVs in the United States.

Several of Nikola’s trucks burned recently in an incident at the company’s headquarters. The cause of the fire is still under investigation, but Nikola said at the time that “foul play” was suspected. The fire remains under investigation.