Tesla CEO Elon Musk found himself intertwined in yet another social media controversy after taking a dig at the United States Senator Bernie Sanders. “I keep forgetting that you’re still alive”, Musk told the 80-year-old lawmaker in a tweet on Sunday.

The tweet, which has been described as “inappropriate” by several social media users, was a response to Sanders’ post earlier on Sunday. He wrote, “We must demand that the extremely wealthy pay their fair share. Period.”

Musk, who has been designated as the richest person in the world, said in a follow up tweet, “Want me to sell more stock, Bernie? Just say the word…”

Musk, who is also the founder of SpaceX, has been making headlines after he said he would sell 10% of his holdings in the company, based on the results of a poll he conducted on Twitter.

Musk has sold another chunk of his stock after pledging on Twitter to liquidate 10% of his holdings in the electric car maker.

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Musk sold about 640,000 shares for roughly $687.3 million, according to two filings Friday with the United States Securities and Exchange Commission. So far this week, the eccentric CEO has sold about 5.1 million shares worth about $5.69 billion, according to reports from Associated Press.

About $1.1 billion of the proceeds that from the sales that were made Thursday will go toward paying tax obligations for stock options granted to Musk in September. The options are part of a compensation package Musk and Tesla agreed to in 2018 that provided the CEO with options if Tesla hit certain financial targets. The company is now profitable and worth more than $1 trillion.

Mellisa Byrne, a former political ally of Sanders and an activist, said in a tweet, “Folks, quit buying Tesla. Don’t reward abusive men”. However, Sanders has still not responded to the comments made on Sunday.