System, Portfolio and Order Management

Although I thought I had a great trading system for quite sometime, I never really put it in real trading. The reason is that in real trading, the dynamic changes of trading system, portfolio positions and orders could have created many scenarios that need to be handled properly by the program code. For example, positions in system and portfolio could be in long, short, flat. Order status could be in Buy, Sell, or no orders. These could have create 3 x 3 x 3 = 27 scenarios. Plus uncertainty caused by real-time trading/market changes, wrong data from brokers, missing or delay of expected submit/cancel/filled events ..., the management of trading system, portfolio position and order becomes a very complicated task. Often a seemly solution may only be found that it will fail under certain situation late, or could cause other functions stop working.

Like a lot of people have said, day trading is a physical job, the tuning of a trading system is too!