The SEC posted its reply brief in support of its appeal in the insider trading case against Mark Cuban, the owner of the Dallas Mavericks. The SEC argues that, as a federal question not controlled by state law, agreeing to keep material, nonpublic information confidential gives rise to a duty of disclosure before using the information for personal benefit in trading, and that a fiduciary relationship between the trader and his source is not required. The SEC further contends that Rule 10b5-2(b)(1) is a valid interpretation of the deception requirement of Section 10(b) of the Securities Exchange Act of 1934, and applies to business relationships.