Musk says he'll sell 10% of Tesla stock based on Twitter poll

Tesla CEO Elon Musk said he would sell 10% of his holdings — worth about $20 billion — in the electric car maker based on the results of a poll he conducted on Twitter over the weekend. Tesla shares slumped about 5% in premarket trading on Monday.

Musk said he would abide by the results of the poll, which ended with 58% of more than 3.5 million votes calling for him to sell the stock. Musk owns about 17% of the 1 billion outstanding Tesla shares. If he sold 10% of his holdings at their current price of around $1,170 per share, it would net him around $20 billion.

But Musk's motivation for selling the stake could be deeper than a push from a Twitter poll, according to the New York Times' DealBook. Musk holds about 23 million stock options, awarded in 2012, that will expire in August. But the grant — valued at about $30 billion — is structured in such a way that he would likely have to pay income taxes when he exercises the options, the report noted. The tax bill could exceed $10 billion.