Kingstree has admitted infringement of two US patents awarded in August for TT's MD Trader system - an order-entry screen that displays multiple prices so that users can judge the depth of a market - which is part of the vendor's X_Trader platform.

In a statement, TT says Kingstree will licence the patents going forward.

The vendor recently settled a claim filed against another Chicago-based broker, Goldenberg, Hehmeyer & Co, which also admitted infringing patents on the same MD Trader technology.

But a patent suit filed against automated fixed income network eSpeed in August this year is still pending. The filing raised the possibility of the lawsuit being extended to other vendors and brokers.

Similar on-screen functionality to MD Trader has been developed by vendors including Orc Software, EasyScreen and Patsystems, and is available in trading systems developed by brokers such as Kingstree Trading and Goldenberg, Hehmeyer & Co.

In a statement released to the Stock Exchange today, Patsystems' says that some of its customers have expressed concerns about the possible effect of TT's actions on the independent software vendor community and the financial industry as a whole.

The vendor says it has for some time been examining a number of different trading methodologies and has brought forward one of these developments into a new version of its existing J-Trader product.

The statement goes on: "In recognition of the commercial advantages inherent in this new methodology, to be called 'Reflector', Patsystems has applied to patent it."

Reflector will also be part of Patsystems' next generation TradeMark platform, which will be introduced progressively from 2005.

Commenting, Kevin Ashby, Patsystems' CEO, says: "I believe that the Reflector trading methodology follows the path of trading system innovation that we initiated some time ago when we began designing our TradeMark platform and that it will put our customers and others in the industry at ease."