Xiaodi Hou, the co-founder of TuSimple who was recently deposed as CEO, has teamed up with another top holder to oust the self-driving trucking company’s board. Short seller Grizzly Research targeted TuSimple last year over its leadership team.

Four TuSimple independent directors have been removed, with co-founder and major shareholder Mo Chen named executive chairman and Cheng Lu returning to the CEO role, the company said in a filing Thursday.

The overhaul, orchestrated by TuSimple co-founders Hou and Chen, comes a week after Hou was removed as chief executive amid an investigation into TuSimple’s relationship with a Chinese startup called Hydron.

Hou took the baton from Lu back in March as part of a so-called “planned executive succession” that took markets by surprise, causing a plunge in the share price.

Last year in August, Grizzly Research put out a short report drawing a parallel between TuSimple and embattled electric truck start-up Nikola, saying both companies had “shady” founders, several common backers, and questionable technology.

TuSimple shares popped 19% Thursday in New York trading but are still down 92% year-to-date.

“We’ve dealt with turmoil this past year, and it’s critical that we stabilize operations, regain the trust of our stakeholders and provide the talented team at TuSimple with the support and leadership they deserve,” said newly installed CEO Lu on Thursday.

The Federal Bureau of Investigation and the Securities and Exchange Commission are said to be looking into TuSimple’s ties with Hydron, a startup working on autonomous trucks mostly in China. TuSimple recently said its own probe found that part of its staff spent paid hours last year working for Hydron and that confidential information had been shared with the Chinese firm.