Just like that, Tesla (NASDAQ:TSLA) founder and CEO Elon Musk has started unloading the billions of dollars worth of stock he left up to a recent Twitter poll. In order to satisfy an upcoming tax bill and to ensure he doesn't look like he's trying to avoid taxes with unrealized gains, the CEO recently asked Twitter users whether they think he should sell 10% of his stake in the electric-car company. With well over half of the respondents voting yes, Musk didn't waste any time to get started.

Here's how many shares of the growth stock Musk has sold already -- and what it means for Tesla investors.

Elon Musk at the groundbreaking event for Tesla's Gigafactory 3 in China.

Tesla CEO Elon Musk. Image source: Tesla.

Musk's $5 billion stock sale

A series of Form 4 filings with the United States Securities and Exchange Commission (SEC) this week revealed Musk has sold a total of over 4.5 million shares in three days. Musk's sales of Tesla Stock on Monday were made under a preset trading plan. Sales on Tuesday and Wednesday, however, were not. These sales are valued at around $5 billion and represent only 2.6% of his stake in the company following the exercising of options on Monday. 

About 3.6 million of the shares he sold during the week will be taxed at long-term capital gains rates, adding to the massive future tax bill Musk is planning for.

Wedbush analyst Daniel Ives, who has an outperform rating and a $1,100 price target on Tesla shares, says the CEO is now likely on pace to complete the sale of 10% of his stake over the next few days. Additionally, Ives seemed to indicate that the sale could ultimately be good for the stock going forward, as it removes the overhang of investors wondering how the CEO would satisfy a tax bill related to exercising stock options.

A bearish or bullish signal?

Of course, Tesla bulls should note that by Musk selling just 10% of his stake in the company, he's currently committing to holding onto 90% of it. That's quite an aggressive stance to hold onto 90% of his stake, considering that this is his first sale since 2016 and that most of his net worth is tied up in the company.

With his approximate $300 billion net worth mostly tied to Tesla stock (he is also the largest shareholder of SpaceX), it's impressive the CEO has maintained about a 20% stake in the $1.1 trillion company since its initial public offering back in 2010. Musk clearly could have cashed out with riches a long time ago but has instead kept his skin in the game. And based on his public declaration to sell just 10% of his stake, he obviously wants to maintain some serious investment in Tesla for now.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.