The US regulators are investigating Elon Musk and his brother Kimbal in connection to insider trading.

The Securities and Exchange Commission (SEC) is enquiring whether Tesla CEO Elon Musk told his brother Kimbal in advance about a Twitter poll, which caused the carmaker’s shares to fall, according to the «Wall Street Journal» (behind paywall).

Tesla shares fell immediately after its CEO asked the public in a Twitter poll in November last year whether he should divest a chunk of his shares to pay taxes.

Kimbal sold 88,500 Tesla shares valued at $108 million a day before the online poll was announced, leaving him with 511,240 shares after the sale, the report says.

In an email sent to the «Financial Times» (behind paywall) Elon Musk denied passing information that could have influenced Tesla’s stock price to Kimbal.

Personal Vendetta

«The idea that I would care about whether my brother might sell shares for a few million dollars less when my Twitter poll caused my own share sale to be over a billion dollars less is utterly absurd,» Musk said to the «FT».

In an apparent reference to the SEC’s Steven Buchholz, Musk added the investigation was «simply more evidence of Stevie grinding his very tiny axe yet again.»

Musk’s lawyers have recently accused the SEC of mounting a harassment campaign against him.