Zach Kirkhorn, Tesla’s CFO and veteran company employee, has quit.

Zach Kirkhorn, Elon Musk’s closest lieutenant at Tesla, resigned unexpectedly from his position as Chief Financial Officer as the electric car maker struggles to cut costs and defend its profit margins after a series of price reductions.

Vaibhav Tania, who has been the chief accounting officer of the company since 2019, was appointed to the position on Friday. The company announced this in a official document published on Monday. Kirkhorn will stay on through the end of this year to assist with the transition, and the company thanked him for “significant contributions”.

Kirkhorn, a 13-year finance veteran of Tesla who took the reins as chief financial officer four years ago, has overseen a turnaround in the company’s finances. Kirkhorn, who has been a finance executive at Tesla for 13 years, was appointed chief financial officer in 2004. Since then, the company’s financial situation has improved dramatically. Its annual free cash flow increased from about break-even to over $7bn.

Tesla shares have increased tenfold since 2019, as the company overcame its Model 3 sedan production issues and delivered 1.3mn cars in 2022.

Kirkhorn did not announce his resignation when he appeared with Musk in the company’s last quarterly earnings callwith Wall Street, less than three weeks earlier. Kirkhorn said that he is “hyper-focused” on cost reductions in the near future to help free up capital for investment. This comes as Tesla prepares to expand its business with the launch of the Cybertruck, and the construction of a new production facility in Mexico.

Kirkhorn’s careful delivery and soft-spoken style were a contrast to Musk, who often left him to translate the latter’s off-the-cuff financial comments into a form that was easier for Wall Street to understand. Kirkhorn’s careful delivery and soft-spoken manner were a contrast to Musk. He was often left to translate Musk’s spontaneous financial remarks into a format that Wall Street could understand.

Kirkhorn explained that Musk had said that Tesla was going to spend $1bn by the end next year on the Dojo supercomputer. The company also provided a forecast for capital expenditures over the next three years. Kirkhorn added that the “movement” was “rapid” and Tesla “continued to update our guidance”.

Taneja became a Tesla employee in 2017 when Tesla acquired SolarCity (Musk’s solar energy company) through a controversial deal. Taneja spent 17 years with PwC, both in India and America, before joining Solar City.