By Jonathan Stempel

(Reuters) - The Chicago Board Options Exchange has sued International Securities Exchange LLC for at least $525 million, accusing its rival of infringing three patents related to an automated options trading system.

In a complaint filed on Monday in the U.S. District Court in Chicago, CBOE said the patents were issued in 2008, 2011 and 2012, and cover systems to monitor quote risk and automatically adjust quotes when risk exposure gets too high.

The Chicago-based unit of CBOE Holdings Inc said these methods are "crucial to market maker participation" and that ISE, a unit of Deutsche Boerse AG , has deprived it of profit and royalties by infringing its patents.

CBOE is seeking a minimum of $525 million to cover what it described as lost profit and reasonable royalties. It is also seeking triple damages if any infringement is deemed willful.

Molly McGregor, a spokeswoman for ISE, declined to comment.

Both exchanges have fought each other for years over a range of intellectual property issues.

CBOE filed its complaint six months after a U.S. appeals court in Washington, D.C. revived ISE's own patent infringement lawsuit challenging CBOE's hybrid trading system, which combines floor-based "open outcry" trading and electronic trading. ISE is an all-electronic platform.

Less than three weeks after the May 7 federal appeals court ruling, an Illinois state appeals court upheld a ban on ISE from listing Standard & Poor's 500 <.SPX> index options, one of CBOE's most profitable products, and Dow Jones Industrial Average <.DJI> options.

The case is Chicago Board Options Exchange Inc v. International Securities Exchange LLC, U.S. District Court, Northern District of Illinois, No. 12-09085.

(Reporting by Jonathan Stempel in New York; Editing by Leslie Gevirtz)