As Tesla nears its deadline to begin Cybertruck production, the person responsible for buying the materials to build the electric trucks is leaving the company. The Information reports that Tesla’s supply chain executive Mustapha El Akkari, who oversaw purchasing of raw materials for the Cybertruck and other Tesla vehicles, is now moving on to rival electric vehicle company Rivian.

According to the report, El Akkari (whose Twitter profile mentions he is Tesla’s head of raw materials) was responsible for $16 billion in supply purchases at Tesla, which included materials like aluminum and steel. Now it looks like El Akkari will be doing similar work for Rivian by accepting a “senior director of structures and raw materials” position, according to a source speaking to The Information.

The Cybertruck’s body is made of stainless steel, which costs more than normal steel typically used in auto manufacturing. In a January earnings call, Tesla CEO Elon Musk said manufacturing of the Cybertruck will begin “sometime this summer,” with mass production to begin in 2024. And in an April earnings call, Musk confirmed a delivery event for Cybertruck is planned for the third quarter of this year.

Rivian has run into supply chain problems during its run-up over the past few years, missing key components to respond to a seatbelt recall that slowed down production. But the company has since made improvements and expects to deliver 50,000 vehicles before the end of 2023.

On the other side, Tesla’s top talent has long been the target of poaching over the years. The company’s former software director for Autopilot moved to Apple in 2021, and another former Autopilot leader left the company to form his own startup. Tesla sued over the move but eventually dropped the case.