In the latest transaction, the world’s richest person got rid of about 934,000 shares, according to regulatory filings dated Thursday. The sales were to help him offset taxes on the exercise of about 2.1 million options. That takes the total of shares sold to 10.1 million for about $10.9 billion since Elon Musk asked his Twitter followers on Nov. 6 whether to offload 10% of his Tesla stake, which would represent about 1.7% of the company’s outstanding stock.

He’d need to sell even more if taking into account the exercisable options he owns. While the majority of his Twitter followers answered “yes” to the poll, Musk had already said in September he was likely to exercise “a huge block” of options toward the end of this year and had established a pre-arranged trading plan to carry out “an orderly sale of shares related to the exercise of stock options,” filings show. With a $284.1 billion fortune, Musk is richer than anyone else in the world, according to the Bloomberg Billionaires Index. His wealth has surged by $128.1 billion this year as Tesla shares have climbed 54%.