| Xetra®, the fully electronic trading platform, offers a comprehensive range of market models by means of which various kinds of securities such as shares, bonds and warrants can be traded. However, other commodities, such as electricity contracts, are also covered by Xetra. The trading system matches buy and sell orders from licensed traders in a central, fully electronic order book. During continuous trading, Xetra examines each buy and sell order and executes it as soon as a suitable offer has been made. In continuous auctions Xetra determines for all open orders the price that leads to the largest turnover. This also ensures efficient trading for less liquid securities. The Xetra software has a modular structure and can be flexibly extended by additional functions. The trading system is based on a client/server architecture. It supports several access options, for instance via the Internet, leased lines, as well as combinations of these two options. Traders can access Xetra using an open interface (Values API). In this way, it is easier to connect in-house systems of the participants and to use the extensive software offering of external distributors. As an alternative, the participant can use the Java-based trading application Xetra J-Trader which is part of the Xetra software. With Xetra Observer we have developed a flexible tool for market surveillance. With this tool, Xetra trading can be controlled and all transactions and prices can be tracked in real-time. Xetra Observer automatically identifies deviations from normally admissible trading activities and signals them through so-called alerts. | 
