Kweku Adoboli, the UBS rogue trader who is facing charges of fraud and false accounting broke down in tears at his trial at Southwark Crown Court yesterday.
Mr Adoboli is accused of losing the bank £1.5 billion in losses by not hedging against derivative trades.
Mr Adoboli sobbed in court saying that he only wanted to do “my job to the best of my ability.”
Prosecutors are trying to prove that Mr Adoboli ignored internal financial controls, including trading limits, and invented false transactions to try and hide his unsuccessful trades to buy himself time to make up the losses.
The prosecution alleges that Mr Adoboli was “intimately aware” of how UBS’s trading controls worked as he had worked in the back office from September 2003 until December 2005 before moving to the trading floor and that he was able to use this knowledge to try and boost his career prospects by disguising the losses that were built up and play the system to his advantage.
However, Mr Adoboli defended himself by saying that using the internal system amounted to finding a way of doing his job.
He said: "It was the ability to understand the interaction of systems and accounting processes that allows you to do your job. It is not fraudulent; it is finding a way to do your job.
"The reality is every single trader, and salesperson, trade support advisor, and settlement person has a duty to understand the system, the tools that we use.
"So I do not think it is fair to say that my experience in settlement and trade support enabled me to more easily do something that has been characterised as fraud.
"Those experiences enabled me to do my job to the best of my ability."
Mr Adoboli went on to tell the court about his relationship with his mentor at UBS, Mike Foster, who was the head at the Exchange Traded Funds (ETF) desk. He said he had a good relationship with Mr Foster, who, Mr Adoboli said, was good at managing him and his colleague, John Hughes.
Mr Foster left before the period in which Mr Adoboli is accused of being involved in false accounting and fraudulent activities.
After he left, John Hughes took over managing the desk which left two men aged 27 and 25 in charge of a $50 million trading book at the height of a culture in the city characterised by excess before the credit crunch helped introduce more checks and balances.
Mr Adoboli said: "Our book was massive. A tiny mistake led to huge losses. We were these two kids trying to make it work."
"Every single bit of effort I put into that organisation was for the benefit of the bank, the people around me and the book I worked on.
Mr Adoboli, 32, of East London, denies two counts of fraud by abuse of position and four counts of false accounting.