TT has sued around sixteen futures brokers over the last two years over its patented MD Trader technology - an order-entry screen that displays multiple prices so that users can judge the depth of a market - which is part of its X_Trader order entry platform.

The US Patent Office has now granted a request filed earlier this year by Chicago-based intellectual property specialist Brinks Hofer Gilson & Lione calling for the re-examination of two patents held by TT.

The law firm claims the order entry system TT patented in 2000 is similar to one adopted several years earlier by the Tokyo Stock Exchange (TSE). The requests for re-examination address whether the patented features were in existence prior to TT's patent filings - thus making the patents invalid.

James Katz, a partner at the law firm, says the granting of the request for re-examination "marks a significant step forward in establishing that these patents are invalid".

But in a separate statement TT argues that the alleged prior art cited in the re-examination request "does not present any new arguments".

"In early 2005, the court considered this same prior art and found that TT showed a very strong likelihood of success on the issue of validity," says the vendor. "Statistically, the overwhelming majority of reexamination requests are granted and TT is confident that the validity of its patents will be upheld."

But the news comes just one month before TT's patent infringement lawsuit against electronic bond trading network eSpeed is set to go to trial at the US District Court for the Northern District of Illinois.

The court recently ruled that the most recent versions of eSpeed's futures trading products Dual Dynamic and eSpeedometer do not infringe any patents held by TT. But the case is still proceeding to trial, which is set to kick of 10 September 2007.

TT is also still contesting suits against GL Trade, CQG and RCG.