1st round: phone interview with two traders, where availability, personal motivation and CV walkthrough is discussed
2nd round: after acing the phone interview you are invited to the trading floor, where trading specific questions are asked. Additionally a orderbook is presented by the trading director and you have to analyze it and figure out the fair price
(recommendation: get to know how market making on german exchanges works, by getting familiar with the exchanges (FWB, gettex, tradegate, quotrix etc). Additionally be open minded and show ability to learn)