His clients have included SAC Capital, the hedge fund firm that pleaded guilty to criminal insider-trading charges in 2013. Atkins was a witness for the firm, now called Point72, in a class-action filed by investors who blamed SAC Capital for their trading losses. Atkins told a court that SAC Capital had a compliance program that was "in accordance with industry norms and best practices" for hedge funds. SAC Capital settled the lawsuit for $135 million in 2016, saying it did so "solely to eliminate the uncertainty, burden and expense of further protracted litigation." Atkins also served as an expert witness in 2013 for Chinese affiliates of the Big Four accounting firms when they faced an SEC enforcement action. Citing Chinese laws that governed information sharing with foreign law enforcement, the firms rebuffed the SEC's evidence requests tied to a series of accounting fraud investigations. The firms eventually settled the case, agreeing to comply in the future and each paying fines of $500,000.