Elon Musk, the world’s wealthiest person, spent much of his weekend sparring with Bernie Sanders on Twitter, after the U.S. senator repeated his call for the ultrarich to pay more tax.

Musk even raised the notion of selling more of his Tesla Inc. shares, which would require him to pay taxes on the gains.

The 80-year-old Sanders, who unsuccessfully sought the Democratic Party presidential nomination in 2016 and 2020, on Saturday tweeted that "we must demand that the extremely wealthy pay their fair share.”