Elon Musk, the billionaire chief executive of Tesla with a penchant for eccentric behaviour, has changed his job title to “technoking” of the electric car manufacturer. In addition to Musk, who also retains his position as chief executive, the company’s financial chief, Zach Kirkhorn, has been rebranded as “master of coin”. Kirkhorn’s job title change is a nod to Tesla’s $1.5bn (£1bn) investment in bitcoin the company made last month, a move which sent shares in the controversial but popular digital cryptocurrency soaring. Musk, who was dethroned as the world’s richest man last month as Tesla’s share price slumped, has previously changed his Twitter biography to “#bitcoin”. “Effective as of 15 March 2021, the titles of Elon Musk and Zach Kirkhorn have changed to technoking of Tesla and master of coin, respectively. Elon and Zach will also maintain their respective positions as chief executive officer and chief financial officer,” the company said in its latest filing to the US stock market regulator, the Securities and Exchange Commission (SEC). The South African-born American entrepreneur, whose net worth is estimated at more than $170bn, second only to the Amazon founder, Jeff Bezos, has a penchant for eccentric and at times divisive behaviour. Earlier this year, Tesla posted a job advertisement for a customer support specialist with responsibilities including handling complaints made against Musk on social media. In 2019, Musk’s theatrical launch of Tesla’s Blade-Runner-meets-cyberpunk pick up truck, designed to prove the company could make a credible electric version of America’s favourite vehicle, descended into farce when durability tests involving sledgehammers, a simulation of a 9mm bullet strike and hefty metal balls went wrong. A year earlier, a decision to smoke marijuana on a live web show resulted in a 6% fall in Tesla’s share price, and the departure of two of its senior executives. Asked about the wisdom of being seen smoking marijuana on the live stream, while he was under investigation by the SEC for tweeting that he had “secured” funding to take Tesla private, Musk told the Guardian by email: “Guardian is the most insufferable newspaper on planet Earth.” The 49-year-old has also been involved in an extended feud with Vernon Unsworth, a diver who helped rescue a team of young football players stuck in an underwater cave in Thailand, after Unsworth criticised Musk’s plan to save them with a submarine. Musk called Unsworth a “pedo guy” on Twitter and referred to him as a “child rapist” in emails to a BuzzFeed reporter. A jury found that Musk did not defame Unsworth, who had been seeking $190m in damages for the tweets. “My faith in humanity is restored,” Musk told reporters in the hallways of the courtroom after the verdict.