Short seller Andrew Left on Thursday filed a securities class action against Tesla and its CEO Elon Musk, accusing Musk in California federal court of manipulating the company’s stock with a controversial tweet about his plans to take the electric-car maker private.

Left, who publishes the online newsletter Citron Research, cited a series of public statements from Musk, including an Aug. 7 tweet in which the business magnate announced he was “considering taking Tesla private at $420. Funding secured.”