Elon Musk, Tesla CEO, stands in the foundry of the Tesla Gigafactory during a press event.Patrick Pleul | picture alliance | Getty ImagesAccording to financial filings out Wednesday, CEO Elon Musk is selling a block of Tesla shares via a plan that he set in motion on September 14 this year. The sales amount to more than 930,000 shares worth over $1.1 billion. He still holds more than 170 million shares.Musk sold these shares in part to satisfy tax obligations related to an exercise of stock options.Before the sale plan was made public, Elon Musk asked his 62.5 million Twitter followers to vote in an informal poll, telling them their vote would determine the future of his Tesla holdings. The filings reveal that, in fact, he knew some of his shares were slated for sale this week.Following the Twitter poll, shares of Tesla slumped more 15% over Monday and Tuesday, before rebounding more than 4% on Wednesday.Previously, Musk signaled that he was likely to sell “a huge block” of his options in the fourth quarter. At an appearance at the Code Conference in September, Musk said when his stock options expire at Tesla, his marginal tax rate would be over 50%.Current and former board members including chairwoman Robyn Denholm, Elon Musk’s brother Kimbal Musk, Ira Ehrenpreis and Antonio Gracias have offloaded hundreds of millions of dollars worth of Tesla shares since Oct. 28 after Tesla’s market cap surpassed $1 trillion.Kimbal Musk sold around $109 million worth of his shares the day before his brother’s Twitter poll and planned sale commenced. This is a developing story, please check back for updates.