Police say former UBS trader Kweku Adoboli made his reckless trades difficult to detect.
Detective Chief Inspector Perry Stokes, who led the investigation said the 32-year-old, was one of the most sophisticated fraudsters he had seen.
Rogue trader Kweku Adoboli who lost £1.4 billion in bad deals at UBS has also been found guilty of a second fraud charge, but acquitted of the four other outstanding false accounting charges.
Kweku Adoboli, who lost £1.4 billion of UBS's money, has been found guilty of one count of fraud at Southwark Crown Court. The jury is still deliberating on other charges.
He admitted the losses but claimed that he was pressured by staff to take risks, culminating in bad deals.
The trial of a City trader from east London accused of losing £1.4 billion while working for Swiss Bank UBS is due to begin.
Kweku Adoboli will appear at Southwark Crown Court in London this morning to face two counts of fraud and two counts of false accounting.
The prosecution case is not expected to open until later in the week.
Adoboli, who is 32 and from Clark Street, Whitechapel, is accused of losing the money in Britain's biggest alleged banking fraud.
He worked for UBS's global synthetic equities division, buying and selling exchange traded funds, which track different types of stocks, bonds or commodities such as metals.
Adoboli is accused of dishonestly using his position to try to make a personal gain, and causing UBS losses or exposing the bank to the risk of loss.It is alleged he lost a total of 2.25 billion US dollars, and charges relate to the period between October 2008 and last September.