Aug 7 Reuters Tesla finance chief Zachary Kirkhorn has stepped down, surprising analysts who considered the company veteran of 13 years as a possible successor to CEO Elon Musk.

The world39;s largest electric vehicle automaker did not give a reason for the departure. Vaibhav Taneja, 45, replaced Kirkhorn as of Friday and will also retain his role as head of accounting. Kirkhorn plans to stay on at Tesla until the end of the year to support a seamless transition, it said.

The depth of Tesla39;s executive bench and the company39;s succession planning have been issues of concern for investors, especially since Musk39;s 2022 purchase of Twitter, now known as X. In addition to his responsibilities at Tesla and X, Musk is also CEO of satellite firm SpaceX and owns brainchip startup Neuralink.

Kirkhorn was seen as an effective and softspoken balance to the more volatile Musk and was one of the most visible executives who often spoke on calls with analysts and made presentations on strategy and products.

He was able to be an effective liaison communicator between Elon and other executives …that would be a skill set that is hard to come by and very valuable but hard to quantify, said Thomas Martin, senior portfolio manager at Globalt Investments, a Tesla investor.

Shares of Tesla were down 1 in trading after the bell.

Kirkhorn39;s departure comes as Tesla readies the first deliveries of its delayed Cybertruck and works to complete a plant in Mexico dedicated to a…