Shares of General Motors (GM 4.46%) 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.
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.
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.
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.