Elon Musk was ordered by a U.S. judge to face most of a lawsuit claiming he defrauded former Twitter shareholders last year by waiting too long to disclose that he had invested in the social media company, which he later bought and renamed X.

In a decision made public on Monday, U.S. District Judge Andrew Carter said shareholders in the proposed class action could try to prove that Musk intended to defraud them by waiting 11 days past a U.S. Securities and Exchange Commission deadline to reveal he had bought 5% of Twitter’s shares.