Kweku Adoboli was working on complex trades in a culture that promised big returns.
Crucially, he had experience working in UBS' backroom operation - this is where the checks and balances take place.
Like Nick Leeson, who brought down Barings Bank 17 years ago, he knew how to hide his fake trades.
There are still many questions about UBS management and how they managed to miss such vast sums: at one stage, the potential losses were £7 billion, double what the bank made in profit the year before all this kicked off.
Could this happen again? Not this specific trade, because the banks know about it now. And there is some evidence that the culture is changing.
But one bank observer told me this evening that he could guarantee there would be new loopholes to exploit and, as a result, more trade crimes.
Andrew Penhale, deputy head of fraud at the Crown Prosecution Service (CPS) said Kweku Adoboli had simply acted dishonestly, and his fraudulent actions had impacted "hugely" on a large number of people. He said:
"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 [Kweku Adoboli] did so by breaking the rules, covering up lying. His actions amounted to fraud, the amount of money was staggering... This was not a victimless crime. People who commit fraud in any walk of life should know that the technicality of the case is not a barrier to bringing it to justice.
Police: Trusted UBS trader turned out to be rogue employee
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.
When you've got a rogue employee in a position of trust it's very difficult when they are intent on breaking the rules to identify what they are doing. As an organisation you put your trust in your employee and if you get a rogue it's very difficult to detect... This isn't someone who has made a mistake in the course of his business, this is someone who has chosen the path that they have gone down. If you're a bad trader, you're a bad trader. He has gone down a different path and he has lied to colleagues.