UPDATE: Mark Cuban responds:  “I am disappointed that the Commission chose to bring this case based upon its Enforcement staff’s win-at-any-cost ambitions. The staff’s process was result-oriented, facts be damned. The government’s claims are false and they will be proven to be so.”

Billionaire and Dallas Mavericks owner Mark Cuban — whose holdings include cable, HD, movie and entertainment companies — is today facing insider trading charges from the SEC over an internet search company’s shares he bought and then sold based on confidential info to allegedly escape a $750K loss. The sports and showbiz loudmouth who’s championed movies coming out the same day in theaters as on DVD can’t be happy about this. My bet is that he links this prosecution to his funding of Sharesleuth.com, a web site to uncover fraud in publicly traded companies, and more recently Bailoutsleuth.com, an online portal for oversight over the $700B government bailout of financial institutions. Then again, Cuban, like Martha Stewart, will find that the SEC likes to go after cases against high-profile individuals as a part of its broader enforcement efforts. Along with his buddy from Broadcast.com days Todd Wagner, Cuban owns Landmark Theatres, a chain of 57 art house cinemas in the U.S.; 2929 Entertainment and Magnolia Pictures, two movie production companies; and HDNet, the first nationwide high-definition cable network. He also was on the 5th season of ABC’s Dancing with the Stars.