What happened

Shares of Tesla (TSLA 1.78%) continued sliding lower on Monday. This extends the growth stock's more than 15% pullback last week. Shares of the electric vehicle (EV) maker fell as much as 5.3% on Monday before recovering a bit to a 4.6% loss as of 12:20 p.m. EST.

The growth stock's decline comes after CEO Elon Musk asked Sen. Bernie Sanders of Vermont if he should sell even more Tesla shares.

A chart showing a stock price falling.

Image source: Getty Images.

So what

"We must demand that the extremely wealthy pay their fair share," Sanders tweeted over the weekend.

"Want me to sell more stock, Bernie? Just say the word ..." replied Musk along with a string of other responses to the senator that were mostly jokes.

Musk recently indicated on Twitter he would sell 10% of his stake in the company so that he doesn't appear to be trying to avoid taxes. In addition, he noted that since he doesn't take a cash salary or cash bonuses that he would have to sell shares to pay taxes.

A tweet by investor Michael Burry, who shorted Tesla at one point earlier this year, might have similarly added to pessimism for the stock on Monday. In a posting that has since been deleted, Burry argued that Musk is simply selling Tesla shares to take advantage of the stock's recent run-up, not to pay taxes. 

Now what

Musk unloaded more than $5 billion worth of Tesla shares last week. To sell 10% of his stake in the company, he'll need to sell about $20 billion worth of stock.

It's unclear whether Musk's spat with Sanders is referring to shares that Musk might have already planned to sell or the proposal to sell even more shares beyond the 10% stake the CEO is expected to dispose of. It's also impossible to know Musk's true motives for selling a portion of his massive stake in the company.