Elon Musk is likely to foot the largest tax bill in history after offloading billions worth of Tesla shares, but he won't be the only billionaire to fork over to Uncle Sam a huge portion of proceeds from stock sales this year.

The Tesla and SpaceX founder, who is the world’s wealthiest person, sold about $14 billion in Tesla shares as this year wound down. Musk was awarded stock options in 2012 that are scheduled to expire next August, and in order to exercise them, he has to pay income taxes on the gains.

Musk’s rapid sell-off began in November, when the billionaire, known for his cheeky Twitter posts, asked his 67 million followers whether he should sell 10% of his Tesla stock holdings in light of congressional discussions about taxing the unrealized capital gains of the ultrawealthy.

“I will abide by the results of this poll, whichever way it goes,” the eccentric billionaires added. “Note, I do not take a cash salary or bonus from anywhere. I only have stock, thus the only way for me to pay taxes personally is to sell stock.”


Some 58% of respondents to the online poll said he should offload the stock. Soon after, Musk sold 3.5 million shares, worth about $4 billion, and followed up with another 934,000 shares worth more than $1 billion.

Since then, Musk has sold off another $14 billion in shares. This week, he revealed to social media users that he will pay over $11 billion in taxes this year, which would be the biggest tax bill in U.S. history.

Several other billionaires have sold big quantities of their holdings as well. As of earlier this month, CEOs and corporate insiders had offloaded a record-breaking $69 billion in stock this year, according to InsiderScore/Verity. That number doesn’t include sales by big institutional holders.

The total volume of sales by insiders is up 30% from last year and a colossal 79% more than the 10-year average.

Ben Silverman, director of research at InsiderScore/Verity, told CNBC that Musk, along with Amazon founder Jeff Bezos, Facebook founder Mark Zuckerberg, and the Waltons of Walmart, accounted for a whopping 37% of that total $69 billion figure.

“The increase in the dollar value of insider sales in 2021 can be attributed to multiple factors, with historically high stock valuations being the primary driver,” Silverman said. “The presence of ‘super sellers’ during the period has helped pump up sales total.”

It is worth noting that a majority of the stocks sold as part of that $69 billion figure were sold through SEC Rule 10b5-1, or prescheduled selling plans.

Microsoft CEO Satya Nadella sold off about half of his company shares last month for some $285 million, with Microsoft attributing the move to “personal financial planning and diversification reasons.” Nadella’s sales could have been driven by changes to the tax code that go into effect in Washington state next year. Starting Jan. 1, a new 7% tax on capital gains will be imposed for amounts over $250,000.

Bezos, also based out of Washington, sold nearly $10 billion in stock in 2021, an amount that is several times more than what he sold prior to the pandemic in 2019 but about on par with his sales last year. He stands to save about $700 million on those sales because he acted prior to the Jan. 1 change.


On a broader level, some experts postulate that some of the sales might be driven out of concern among investors that the stock market’s soaring highs, propped up by the Federal Reserve keeping interest rates at unprecedentedly low levels, might be part of a bubble that is doomed to pop.

Anxiety about the future of the stock market has been lingering for months. Back in April, E-Trade conducted a survey of active investors that found 69% of respondents thought the country was fully or somewhat in a market bubble, despite a rise in bullish sentiment at the time.

A bubble is when prices for a stock or asset continue to rise over time in excess of that stock or asset’s intrinsic value. Those elevated prices are driven by speculative buying and the bandwagon effect of other investors seeing those prices grow ever higher and wanting to get in on the action. That price inflation is followed by a precipitous drop in value as investors suddenly sell off those assets in a domino effect, sending the stock’s value into a freefall.

The simple fact that stocks are valued so high right now might also make it prudent for major investors to sell. For example, Gerber Kawasaki, a major shareholder in Tesla, pointed out that given the company’s breakneck growth in 2021, it just makes good financial sense to cash out some of those earnings.

“Every major tech entrepreneur and Bitcoin owner is cashing out huge amounts of capital right now for huge profit, so for Musk to take some money off the table is a smart move, and he just announced it in a very Muskian way,” he said.

Part of this year’s record stock sell-off likely also had to do with potential changes to public policy. When President Joe Biden floated his economic plan, known as Build Back Better, earlier this year, he proposed enormous changes to the tax code, which would have given the government a much bigger chunk of stock sales if it had passed.

Biden and Democrats had proposed increasing the top marginal tax rate on individuals making over $400,000 per year to 39.6%, up from the current 37% rate. The White House also sought to nearly double the capital gains rate for the highest earners from 20% to a new rate of 39.6%. People making more than $1 million would have also faced a federal rate of up to 43.4% when an existing Obamacare surtax on investment income is considered.

“Potential tax rate and code changes at the federal and state level are likely a motivator for some sellers,” said Silverman.


Those tax proposals were both nixed, and even the Build Back Better Act itself appears likely to be dead in the water after centrist Democratic Sen. Joe Manchin signaled this week that he will not be throwing his support behind the legislation. Democrats couldn’t afford to lose the West Virginia senator’s vote, as the Senate is evenly split with Republicans.