In early trading, Tesla’s shares were off as much as 9 percent.

But in a filing with the Securities and Exchange Commission on Friday, Tesla said Morton had given notice of his resignation Tuesday and that it was effective immediately.

“Since I joined Tesla on Aug. 6, the level of public attention placed on the company, as well as the pace within the company, have exceeded my expectations,” Morton said in a statement included in the filing. “As a result, this caused me to reconsider my future. I want to be clear that I believe strongly in Tesla, its mission, and its future prospects, and I have no disagreements with Tesla’s leadership or its financial reporting.”

Morton had been hired from the data storage company Seagate to replace Eric Branderiz, who left Tesla in March.

Nearly a dozen top executives have left Tesla this year. Sarah O’Brien, vice president for communications, and Gabrielle Toledano, the head of human resources, have departed in the last few weeks.

The upheaval that began with the abortive bid to take the company’s shares off the public market has deeply dented Tesla’s stock — the shares have lost one-third of their value since early August — and brought new scrutiny of Musk’s behavior and managerial fitness.

The sudden resignation of Morton could be of interest to securities regulators. The San Francisco office of the Securities and Exchange Commission is investigating not only Musk’s unusual tweet about having “funding secured” to take the car company private, but broader issues surrounding company disclosures about production goals with its latest offering, the Model 3.

A company spokesman, Dave Arnold, had no comment.

This article originally appeared in The New York Times.

Neal E. Boudette and Ceylan Yeginsu © 2018 The New York Times