(Reuters) - Billionaire investor William Ackman on Thursday announced changes to the structure of his blank check firm and said that a lawsuit filed earlier this week against him could have a “chilling effect” on the hugely popular SPAC industry by making it tougher to find a suitable company to merge with. Reporting by Svea Herbst-Bayliss; Additional reporting by Radhika Anilkumar in Bengaluru; Editing by Shri Navaratnam Our Standards: The Thomson Reuters Trust Principles.