Complex sentence: At the SEC, his department conducted investigations about improprieties, conflicts of interest, and the SEC's failure to uncover Ponzi schemes, referring about 30 cases to the Justice Department, of which 2 were prosecuted, leading to 1 conviction.
Split into simpler sentences: At the SEC, his department conducted investigations about improprieties, conflicts of interest, and the SEC's failure to uncover Ponzi schemes. He referred 30 cases to the Justice Department; 2 were prosecuted, leading to 1 conviction.