Kweku Adoboli, a trader at UBS's London office, built unauthorized positions in equity ETFs totaling approximately $23 billion — far exceeding his trading limits. He concealed the positions by entering fictitious offsetting trades in the bank's systems, creating the appearance of a hedged, low-risk book.
In September 2011, as markets declined, Adoboli's positions lost value rapidly. UBS discovered the unauthorized trades and unwound the positions, crystallizing a $2.3 billion loss — the largest rogue trading loss in UK history at the time.
Adoboli was convicted of fraud and sentenced to seven years in prison. The case exposed failures in UBS's internal controls: the fictitious trades were not verified, and Adoboli's positions exceeded his limits without triggering alerts. The case illustrated how a trader who understands the control system can exploit its gaps, and how the assumption that internal records are accurate is the foundation of every risk model.
UBS lost $2.3B, the UK's largest rogue trade, because controls verified numbers, not existence; Adoboli's fake offsetting trades looked hedged until markets fell.
Adoboli built $23B in unauthorized positions, hiding them with fictitious offsetting trades.
UBS's internal controls did not verify the fictitious trades or flag the position limit breaches.
The $2.3B loss was the largest rogue trading loss in UK history.
Adoboli was sentenced to seven years in prison.
Internal controls that don't verify the existence of trades are a filing system, not a control. Adoboli's fake trades passed every check because no one checked if they were real.
Adoboli was sentenced to seven years. UBS overhauled its trading controls and position monitoring. The case prompted regulators to strengthen requirements for trade verification and position limit enforcement.
FOLLOW THE EVIDENCE