Elon Musk admits to exhaustion as tweet storm deepens

Entrepreneur Elon Musk has acknowledged exhaustion from overwork, as he deals with a reported probe by regulators into a plan divulged on Twitter to take his auto company Tesla private.

"This past year has been the most difficult and painful year of my career," Musk told the New York Times in an interview on Thursday. "It was excruciating."

The paper said the electric car company's swashbuckling boss choked up at times during the interview as he talked about working marathon hours trying to meet production deadlines.

Musk, who founded Tesla in 2003 to push cars into a new tech era, said he saw last week's tweet -- which included an assurance that funding for going private was secured -- as an attempt to be transparent.

Impact on Tesla shares

The news sent Tesla shares soaring so much that trading was suspended in New York.

It shocked investors, market analysts and reportedly even Tesla board members who did not see it coming, as well as attracting the attention of regulators.

Tesla shares fell this week on reports by Fox Business and the New York Times that the US Securities and Exchange Commission has subpoenaed Musk to talk about the tweet.

Normally such a major announcement -- taking a huge company private -- would be explained in detail beforehand to regulators.

He and other board members are preparing to meet with SEC officials as early as next week, the Times said.

Musk acknowledged that no one read his Twitter post before he sent it, but said he did not regret it. "Why would I?" he said.

Musk, who envisions sending tourists to the Moon, is recognised as one of the most influential innovators in the United States.