Faruqi & Faruqi has begun an investigation into company following its sale to Matson, it said in a statement picked up by news wires.
Juan Monteverde, a partner in the firm, is looking into potential breaches of fiduciary duties by Horizon directors relating to the price achieved, the statement said. The deal was agreed at $0.72 per share.
According to Ben Nolan of Stifel Matson is paying $541m for the primary assets changing hands in the deal.
Matson