Elon Musk has now unloaded more than $10 billion in Tesla Inc. stock as the billionaire’s share-selling spree involving his holdings in the electric-vehicle maker stretched into a second month.

Mr. Musk on Thursday sold more than 934,000 Tesla shares valued at just over $1 billion, according to regulatory filings. The sales came as Mr. Musk exercised more than 2.1 million vested Tesla stock options.

The...

Elon Musk has now unloaded more than $10 billion in Tesla Inc. stock as the billionaire’s share-selling spree involving his holdings in the electric-vehicle maker stretched into a second month.

Mr. Musk on Thursday sold more than 934,000 Tesla shares valued at just over $1 billion, according to regulatory filings. The sales came as Mr. Musk exercised more than 2.1 million vested Tesla stock options.

The chief executive began selling shares on Nov. 8. Nearly two months earlier, on Sept. 14, he had established a plan to exercise at least some of his nearly 23 million vested stock options set to expire in August 2022 and to sell some of the shares to cover tax withholding obligations. The latest transactions are part of that plan, according to the disclosures.

Mr. Musk last month polled Twitter users about whether he should sell 10% of his Tesla stock, and people on the social-media platform who voted endorsed the idea. Based on his total holdings before the Twitter poll, Mr. Musk likely would need to sell more than 12 million additional shares following his latest transactions to hit the Twitter target. The precise number depends on how he defines his ownership stake.

Mr. Musk has a net worth of around $284 billion, making him the richest person on the Bloomberg Billionaires Index.

Tesla’s stock price has slumped since Mr. Musk began his selling last month. It closed Thursday at $1,084.60, down 0.9% for the day and more than 11% since Mr. Musk took the Twitter poll.

Write to Robert Wall at robert.wall@wsj.com