What happened
Shares of General Motors (GM -1.88%) were trading lower on Friday morning following the abrupt departure of Daniel Ammann, a longtime GM executive who was most recently CEO of GM's important Cruise self-driving subsidiary.
As of 10:30 a.m. ET, GM's shares were down about 6.4% from Thursday's closing price.
So what
Auto investors were surprised by the news of Ammann's departure, which was announced by GM in a terse press release after the U.S. markets closed on Thursday. Ammann, a former Morgan Stanley analyst who joined GM after it emerged from bankruptcy, had become a stalwart of CEO Mary Barra's senior team and the leader of its self-driving efforts.
Ammann's past roles had included stints as GM's chief financial officer and as its president, a role akin to chief operating officer. He had been Cruise's CEO since 2018.
Dan Ammann (right), shown here with Cruise co-founders Daniel Kan and Kyle Vogt, became CEO of the self-driving start-up in 2018. Ammann abruptly left the company on Thursday. Image source: General Motors.
GM didn't say why Ammann left, where he might be going, or really much of anything else. The release simply noted his departure and said that Cruise co-founder Kyle Vogt will serve as interim CEO until a permanent replacement is found.
The strong suggestion is that his departure was abrupt, unplanned, and -- perhaps -- not his choice.
Now what
Cruise is a major component of the bull case for GM's stock. The company is expected to launch self-driving taxi services in several cities next year.
Ammann's abrupt departure raises some big questions. Did Ammann leave because of a personal scandal? Is he joining a competitor? Did Cruise's business miss key milestones? Did he and Barra have a disagreement about strategy?
The uncertainty is why the stock is down today, of course. I expect that GM will provide an update on Cruise's business and its go-to-market plan in due course, certainly no later than GM's fourth-quarter earnings report early next year.
But investors should keep in mind that if Ammann was fired because of a personal scandal of some kind, GM might not ever tell us exactly what happened.
