Tesla CEO Elon Musk’s sales of his company’s stock continued Monday. His latest filing promises more are coming.

Musk sold another $931 million worth of stock on Monday, bringing his total sales of stock during the last six trading days to $7.8 billion. He has sold some shares each of those days.

Monday’s Tesla stock sales are part of a plan he established two months ago to exercise an even larger block of stock options before they expire next August. Company insiders such as CEOs are allowed to establish a stock-selling plan so the sales take place automatically without being affected by non-public information they may have about the company.

The sales follow a Twitter poll he conducted on November 6 and 7, in which he asked followers if he should sell 10% of his stake in the company in order to increase his taxable income. But the sales on Monday were driven more by the need to exercise stock options he holds before they expire next August, coupled with the requirement that he pay taxes on those shares once he does so.

The filings he made with the Securities and Exchange Commission Monday said the latest sales were done “solely to satisfy [Musk’s] tax withholding obligations related to the exercise of stock options to purchase 2,107,672 shares as reported herein.” And it said he was exercising the stock options, which are due to expire in August 2022 in order to have an “orderly sale of shares related to the exercises of the options” before they expire.

The exercise of options Monday and the subsequent sales were nearly identical to transactions he completed on Monday of last week.

On November 8, Musk exercised 2.2 million options and sold 934,000 shares for $1.1 billion. On Monday he exercised 2.1 million options and again sold 934,000 shares. The difference in the money he received for the sales was due to the drop in price of Tesla shares over the course of the last week. The number of sales he sold is one of the factors pushing down the price of the stock.

The net value of the stock at the time the options are exercised will be treated as taxable income, taxed at a federal take rate of 40.8%. He could end up with a federal tax bill approaching $10 billion once he exercises all of those soon to expire options, depending about the value of the stock at the time the shares are purchased.

The other sales he completed between last Monday and this Monday came from the Tesla shares he already held outright. Musk held most of those shares since Tesla’s 2010 initial public offering. Those sales will only be taxed as a long-term capital gain at a 20% tax rate.

The stock sales still reflect less than 5% of his Tesla shares. That, and the fact that he still owns options to buy an additional 18.6 million shares, all of which are due to expire next August, means additional stock sales are virtually certain.

The-CNN-Wire™ & © 2021 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.