activities." Barclays, which received a 30 percent discount on the fine for settling early, said the FCA made no finding that the bank facilitated any financial crime in relation to the transaction or the clients on whose behalf it was executed.
"Barclays has cooperated fully with the FCA throughout and continues to apply significant resources and training to ensure compliance with all legal and regulatory requirements," it said.
The FCA said the failings were not identified by Barclays, however. It was only after the regulator discussed the transaction with the bank that it gathered more information on the relationship with the clients.
The deal's size meant "very significant" harm could have been done to the integrity of the UK finance system and society if it had been related to criminal activity, the FCA said.
The fine is the seventh significant penalty imposed on Barclays by Britain's regulator in the past six years, including penalties for allegedly manipulating Libor interest rates and foreign exchange prices.
The series of scandals means improving standards and culture will be a key task of the bank's new Chief Executive Jes Staley, who starts on Tuesday.
The FCA said several members of Barclays' senior management were aware of and endorsed the transaction, and said five individuals were identified as giving part approval for it, but it did not name any individuals at fault.
It said the bank set up "a select team", including senior managers, to carry out checks and arrange and execute the deal, which was known by those involved within Barclays as an "elephant deal" because of its size.
Bob Diamond was the chief executive of Barclays from the start of 2011 until he left in July 2012. The head of its wealth management business in 2011 and 2012, which oversees dealings with rich clients, was Tom Kalaris. He stepped down in May 2013. A spokesman for Diamond declined to comment, while Kalaris could not immediately be reached for comment.