Tesla CEO Elon Musk mocked the Securities and Exchange Commission in a tweet Thursday, calling the agency the "Shortseller Enrichment Commission," days after settling fraud charges brought against him by the agency.

The tweet, which is missing a word and appears to take a sarcastic tone, says "the Shortseller Enrichment Commission is doing incredible work" and commends the SEC on a name change that did not occur.

Musk doubled down on the remark when another Twitter user said Musk needs a "a social team that can get attention without typos and without enraging the Shortseller Enrichment Committee."

The Tesla CEO asked, "Why would they be upset about their mission? It's what they do."

Shares of the automaker fell more than 2 percent after hours following the tweet. The stock was already down 4.4 percent during regular hours.

Late last week, Musk reached an agreement with the SEC to settle fraud charges in connection with an Aug. 7 tweet about taking the company private. Musk claimed at the time the necessary funding had been secured — a claim the SEC alleged was "false and misleading."