Elon Musk’s recent acquisition of 9.1% of Twitter became the subject of a securities class action suit Tuesday in the Southern District of New York, with investors alleging that the Tesla and SpaceX founder acquired less expensive Twitter shares because he did not disclose his ownership in a timely manner.

Block & Leviton represents lead plaintiff Marc Bain Rasella in the proposed class action, which was filed on behalf of investors who sold Twitter stock between March 24 and April 1.