A City trader who lost £1.4bn ($2.2bn) of Swiss bank UBS's money has been jailed for seven years after being found guilty of two counts of fraud.
Southwark Crown Court heard Kweku Adoboli was "a gamble or two away from destroying Switzerland's largest bank".
He lost the money in "unprotected, unhedged, incautious and reckless" trades, the jury was told.
Adoboli, 32, of Whitechapel, east London, was cleared of four charges of false accounting.
He had denied the charges, which related to the period between October 2008 and September 2011.
Adoboli, who was arrested on 15 September 2011, worked in UBS's global synthetic equities division, buying and selling exchange-traded funds (ETFs), which track stocks, bonds and commodities.
He had joined the bank in 2003 and became a trader in 2006.
The court was told that at one point he stood to lose the bank £7.5bn ($12bn).
Adoboli, the Ghana-born son of a diplomat, told the jury his senior managers were aware of his actions and encouraged him to take risks.
He claimed he lost control over his trades during a period of market turbulence last year.
In his sentencing remarks, the judge, Mr Justice Keith, told Adoboli: "Whatever the verdict of the jury you would forever have been known as the man responsible for the largest trading loss in British banking history.
"Your fall from grace as a result of these convictions is spectacular. The fact is you are profoundly unselfconscious of your own failings....
"There is a strong streak of the gambler in you. You were arrogant to think the bank's rules for traders did not apply to you."
'Magic touch'
The first verdict returned by the jury saw Adoboli convicted of one count of fraud relating to unauthorised trading leading to the £1.4bn loss to UBS.
The judge then gave the jury a majority verdict direction, saying they could deliver a 9-1 verdict on the second fraud charge and the four false accounting charges.
The jury had been reduced to five men and five women after two jurors were discharged.
They found Adoboli guilty by a majority verdict of the second fraud but acquitted him of the other charges.
The prosecution said Adoboli had been a gambler who believed he had the "magic touch".
But, giving evidence, Adoboli said everything he had done was aimed at benefiting the bank, where he viewed his colleagues as "family".
Adoboli said he had "lost control in the maelstrom of the financial crisis", and was doing well until he changed from a conservative "bearish" position to an aggressive "bullish" stance under pressure from senior managers.
He told the jury that staff were encouraged to take risks until they got "a slap on the back of the wrist".
'Wanted it all'
After the verdicts, Andrew Penhale, deputy head of fraud at the Crown Prosecution Service, said: "Behind all the technical financial jargon in this case, the question for the jury was whether Kweku Adoboli had acted dishonestly, in causing a loss to the bank....
"He did so, by breaking the rules, covering up and lying. In any business context, his actions amounted to fraud, pure and simple.
"The amount of money involved was staggering, impacting hugely on the bank but also on their employees, shareholders and investors. This was not a victimless crime."
He added: "At the heart of any complex fraud is a simple notion of dishonesty which is something that we can all understand."
Det Ch Insp Perry Stokes, from the City of London Police, which investigated Adoboli, said: "This was the UK's biggest fraud, committed by one of the most sophisticated fraudsters the City of London Police has ever come across.
"To all those around him, Kweku Adoboli appeared to be a man on the make whose career prospects and future earnings were taking off. He worked hard, looked the part and seemingly had an answer for everything.
"But behind this facade lay a trader who was running completely out of control and exposing UBS to huge financial risks on a daily basis.
"Rules put in place to protect the bank's position and the integrity of the markets were being bypassed and broken by a young man who wanted it all and was not willing to wait.
"When Adoboli's pyramid of fictitious trades, exceeded trading limits and non-existent hedging came crashing down, the repercussions were felt in financial centres around the world."
In a statement, UBS said: "We are glad that the criminal proceedings have reached a conclusion and thank the police and the UK authorities for their professional handling of this case."
