As looming tax increases and high share prices push many people to profit, CEOs and corporate executives have sold record amounts of stock.

Start at Satya Nadellaat MicrosoftTo Jeff Bezos Elon MuskInsiders, founders, and CEOs are cashing in stock at an unprecedented rate. Insider sales are now up by 30%, from 2020 to $69 Billion, and 79% over a 10-year-average, according to InsiderScore/Verity. This excludes large institutional investors.

Because December is an often active month in sales because of tax planning, the selling will likely increase.

While some market watchers see insider selling as a warning sign signal of a market top, many of the stocks sold by the insiders — including Tesla and Amazon — have continued to surge after the selling. The majority of stocks sold were in prescheduled selling programs, also known as the 10b5-1 program.

Musk and Bezos were the top sellers this year with around $10 billion of stock sales. Ben Silverman, director of research at InsiderScore/Verity said the top four “super sellers” — Musk, Bezos, the Waltons and Mark Zuckerberg — account for 37% of this year’s total.

He said that the increase in insider sales’ dollar value in 2021 could be explained by many factors with historically high stock values being the main driver. Sales totals have been helped by “super sellers” during that period.

Musk bought another $1.05 billion in Tesla stockAs part of his options exercise and tax payments. His sales since his famous Twitter poll on Nov. 6Now, the total amount is $9.85 Billion. About half goes to options-related taxes while the other half can be used for cash-outs.

Jeff Bezos made a record $9.97 trillion in Amazon stock sales this year. His activity falls in line roughly with his stock sales last yearThey are far greater than the sales he made in 2019, and four times more than those of his earlier sales of $1 million per year. The Securities and Exchange Commission has filed paperwork proving that the sales figures are part of a 10-b5-1 plan.

The Walton Family has been able to sell $6.18Billion in WalmartStock this year via their family trust or investment vehicle. They sell shares regularly to preserve their ownership level and help fund their philanthropic endeavors. Mark Zuckerberg is the owner of $4.47 trillion in shares. MetaThis year, stock as part of the 10b5-1 Plan. Google founders Larry Page Sergey BrinThey have all sold around $1.5 Billion of their products AlphabetAs part of 10b5-1 plans, shares

The sales are not just driven by scheduled selling programs. Taxes and high values also drive the business. Satya Nadella, Microsoft CEO, sold nearly half his Microsoft shares for $285 million last month. In a statement, the company stated that it had been done to “personal financial planning” and for diversification.

Nadella also will save taxes by selling earlier than next year. Washington’s new capital gains tax will be 7% effective January 1. Nadella can save as much as $20 million by selling before the increase in taxes. Bezos can save as much as $700 million on Washington state taxes by selling before January.

High-earners are likely to see their federal taxes rise, which could lead some CEOs and others to take the plunge to get out of paying them. House members have proposed an increase of 5% to incomes above $10million and 8% to incomes over $25million.

Silverman explained that sellers may be motivated by potential changes in the tax code and rate at the state or federal level.

Stock valuations are perhaps the largest factor that drives up sales. Adam Aron is the CEO and founder of AMC EntertainmentThe price of a cigarette has increased by more than 1,500% in the past year. 625,000 shares of AMC stockThe company’s shares were sold last month for approximately $25,000,000. As part of his plan to sell 1.25million shares, which he explained to investors during an earnings call, was prudent estate planning in light of the potentially high capital gains tax rates. He also noted that there have been significant changes made to how one can leave heirs.