Tesla Inc. co-founder and CEO Elon Musk mocked the SEC through a tweet on Oct. 4, hours after a federal court judge ordered him and the securities regulator to justify their securities fraud settlement, Reuters reported Oct. 4.

"Just want to [sic] that the Shortseller Enrichment Commission is doing incredible work," Musk wrote on Twitter.

Reuters said Musk's tweet came less than four hours after U.S. District Judge Alison Nathan ordered Musk and the SEC to explain in a joint letter why their settlement, which let Musk remain as CEO, was fair and reasonable. Under the settlement, Musk agreed to resign as chairman of the California-based electric car company and distribute $40 million in penalties to affected investors.

The settlement relates to Musk's Aug. 7 tweet, in which he indicated that funding is in place to take Tesla private at $420 a share. The SEC sued Musk weeks later, accusing him of misleading investors.

"The court has a duty to ensure the proposed consent judgment is "fair and reasonable," Judge Nathan wrote.

In a separate tweet, Musk said, "People sometimes forget that a company is just a group of people gathered together to make products. So long as it makes great products, it will have great value."