Musk tweeted on Feb. 19 that "Tesla made 0 cars in 2011, but will manufacture about 500,000 in 2019." Regulators say that Musk has not requested or received prior approval before publishing the tweet, in accordance with the terms of the settlement agreement.
A few hours later, Musk sent a follow-up tweet stating that the company will actually deliver only 400,000 cars this year.
SEC's SEC complaint to the SEC on Monday led to a 4% drop in Tesla shares after trading hours.
The SEC said Monday that Musk had "not made a diligent or good faith effort" to comply with the settlement.
"The only tweets that should be … examined would be if a tweet had a probability of causing a movement in the stock," he said. "Otherwise, it's – hello, first amendment."
Musk also said in the interview that he did not "respect" the SEC.
Last August, the billionaire had trouble with the regulators after a series of tweets about a possible transaction to privatize Tesla.
Musk said it had secured the necessary financing to acquire Tesla's $ 420 private share, prompting a sharp rise in the company's shares. But he did not get the funding, according to the SEC.
Tesla and Musk's lawyers did not immediately respond to requests for comments on Monday.