In Friday's premarket, General Motors shares fell over 3% as the company announced that Dan Ammann, the CEO of its self-driving car subsidiary Cruise, is stepping down with immediate effect.

The startup is waiting for approval to run a self-driving car service in San Francisco, so Ammann's departure seems timely.

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Cruise applied to the California Public Utility Commission last month for permission to charge for rides in self-driving cars without a safety driver. According to a major newswire, General Motors CEO Mary Barra expects the company to generate $50 billion in sales in the next six years.

Ammann was a significant figure in GM's acquisition of Cruise in 2016, and he was designated the unit's CEO in 2019. According to A major newswire, the leaving CEO had restricted ownership in the business, with the possibility of a windfall if the company went public — "a long-term consideration" in Barra's words.

Kyle Vogt, the company's founder and president and chief technology officer, will act as interim CEO. Wesley Bush, the former chairman and CEO of Northrop Grumman and a member of the General Motors board of directors, will join the Cruise board, according to GM.

According to GM, Cruise will play a key part in the development of its autonomous vehicle platform, which will be used to pursue markets other than ridesharing and delivery.