Last weekend, Musk said he would sell 10% of his holdings in the company, based on the results of a poll he conducted on Twitter. The sale tweets prompted heavy selling in the stock Monday and Tuesday. Shares fell four out of five days this week, and they dropped 2.8% Friday.
While the stock has slid 15% this week, over the last 12 months it's up 150%.
Musk is Tesla's largest shareholder and is the wealthiest person in the world, according to Forbes, with a net worth of around $278.7 billion.
Tesla Inc. is based in Palo Alto, California, although Musk has announced the company will move its headquarters to Texas.