PALO ALTO (CNN) — The Securities and Exchange Commission has asked a federal judge to hold Tesla CEO Elon Musk in contempt of a settlement deal reached last year.

The request from regulators in a court filing Monday sent the carmaker’s stock plummeting more than 4% after hours.

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The US government’s ask is tied to a claim from Musk on Twitter last week that “Tesla made 0 cars in 2011, but will make around 500k in 2019.”

Regulators say that Musk did not ask for or receive pre-approval before publishing the tweet, per the terms of the settlement agreement.

He later had to send a follow-up tweet indicating that the company will actually deliver just 400,000 cars this year.

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