Less than a week after settling with the U.S. Securities and Exchange Commission, Tesla Inc. CEO Elon Musk took to Twitter to insult the agency.

Following Musk’s tweet, Tesla shares fell 2.4 per cent to US$275 after the markets closed in New York.

Musk agreed to settle the agency’s case against him on Sept. 29. The deal required him to give up the chairman role at the automaker and to pay a US$20 million fine.