Phil Stern, who has worked in enforcement for the Securities and Exchange Commission, said SEC charges are generally handled as criminal cases "when they're viewed to be egregious in terms of the number of people affected or if there's something out of the ordinary."

The fact that Cuban is a well-known public figure "in and of itself wouldn't cause the U.S. attorney to step in," he said, the Fort Worth, Texas, Star-Telegram reported Tuesday.

The SEC Monday charged Cuban with selling 600,000 shares of Mamma.com stock in 2004 after learning the company was about to issue discounted shares, which typically reduce the value of the stock, at least temporarily.

Cuban has denied the charges.

Whether criminal charges are ever filed, however, attorney Julia McDonough, who has represented clients in SEC cases, said Cuban's fame ensures the SEC "will get a lot of bang for their buck," the newspaper reported.