Hyliion Holdings Corp. and certain officers face a securities class action alleging that the company made false or misleading statements and failed to disclose material information about a recently formed deal partner and the timing of related stock-price appreciation. The proposed class covers people and entities that purchased or otherwise acquired Hyliion securities from May 12, 2026, through June 23, 2026, inclusive. The complaint alleges that the deal partner did not appear to have actual business operations and that Thomas Healy, Hyliion's Chief Executive Officer, and Jon Panzer, its Chief Financial Officer, timed the announcement and resulting price increase to facilitate insider trading. Investors who suffered losses have until Oct. 27, 2026, to ask the court to appoint them as lead plaintiff, although participation in any recovery does not require serving in that role. Bronstein, Gewirtz & Grossman, LLC says it represents investors on a contingency-fee basis and seeks reimbursement of expenses and attorneys' fees only if successful.