Executives of a failed health care financing company defrauded investors of $1.9 billion and took part in a “massive cover-up” to hide their dealings, the government said in opening arguments of a federal trial in Columbus, Ohio, on Thursday.

Attorneys for two former owners and three senior executives of National Century Financial Enterprises denied the allegations before jurors at the outset of their trial for one of the largest alleged white-collar crimes after Enron or WorldCom.