Mutli-agent based simulation models allow for the research of economic questions differently than before. This thesis builds a multi-agent based simulation model of the U.S. financial market, to examine the behavior of banks within it. Although the focus is on the credit market, a sub-goal is to build a complete model of the market. This is due to the observation, that in the 2007 financial crisis, seemingly small adjustments in one market of the U.S. led to a world-wide shock to the financial system. While designing, some existing ACE-models are adapted as well as new ones incorporated. The simulation model includes ideas for models of banks, hedge funds, the Federal Reserve System, a stock trading simulation, an information market and federal, as well as corporate and private household, credit customers.