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.