$Tesla(TSLA.US)$ CEO Elon Musk sold shares worth $963.2 million on Thursday, as per filings made with the U.S. Securities and Exchange Commission. 

What Happened: Musk sold 934,091 shares of Tesla and also exercised options to purchase 2.17 million shares of the automaker at $6.24.

As per the filings, the shares were "sold solely to satisfy the reporting person's tax withholding obligations."

Price Action: On Thursday, Tesla shares declined 6.1% to $1,003.80 in the regular session and dropped another 2% in the pre-market trading on Friday.

Why It Matters: At the beginning of the month, Musk sold Tesla shares worth $1.01 billion and exercised options to buy 2.1 million shares. 

Musk polled his Twitter audience in early November if he should sell 10% of his holdings in Tesla.

Across the S&P500, insiders have sold $63.5 billion in shares through November. This is a rise of 50% compared with 2020, reported The Wall Street Journal.

The technology sector dominated these sales with $41 billion in sales across the market, as per the Journal.

Musk's 31-day total sales amount to 11.0 million shares, 64.7% of target. The sales amount to $11.8 billion at an average price of $1,073, according to a Twitter post by Gary Black, the managing partner at The Future Fund LLC, an SEC-registered investment advisor.

2/ I'm hopeful @elonmusk will stop allowing $TSLA shorts to front run his sales of 934,091 10b5-1 $TSLA shares each week. No other CEO selling this amount of stock would enable HFs to jump in front of sales. Elon should do a secondary to sell his remaining 6M shares (<1% float).

— Gary Black (@garyblack00) December 10, 2021

Black said he hoped Musk will stop allowing Tesla shorts to "front-run" his sales each week. "No other CEO selling this amount of stock would enable HFs to jump in front of sales," Black said in a separate tweet. 

Notably, the Tesla CEO does not receive a salary and is compensated instead through a stock options plan.