The financial regulator said Barclays had been fined for failing to adequately manage conflicts of interest between itself and its customers between 2004 to 2013.

The FCA said that former trader Daniel James Plunkett exploited weaknesses in Barclays’ systems and controls to influence the gold prices in order to profit at a customer’s expense.

Plunkett was responsible for pricing and managing Barclays’ risk on a digital exotic options contract that referenced the price of gold during the 3.00 pm Gold Fixing on 28 June 2012.

If the price fixed above $1,558.96 at 3.00 pm, then Barclays would be required to make a payment to its customer. But if the price fixed below this, Barclays would not have to make that payment, the FCA said.

The FCA said that Plunkett placed certain orders with the intent of increasing the likelihood that the price of gold would fix below the barrier, which it eventually did.

As a result of Plunkett’s actions, Barclays was not obligated to make a $3.9 million payment to its customer, who was later compensated in full by the bank.

Plunkett has been fined £95,600 and banned from performing any function in relation to any regulated activity.

“Barclays’ failure to identify and manage the risks in its business was extremely disappointing. Plunkett’s actions came the day after the publication of our LIBOR and EURIBOR action against Barclays. The investigation and outcomes in that case meant that the firm, and Plunkett, were clearly on notice of the potential for conflicts of interests around benchmarks,” said Tracey McDermott, the FCA's director of enforcement and financial crime.

The FCA has acknowledged that Barclays brought the conduct of the former trader promptly to the attention of its predecessor, the Financial Services Authority and that Barclays also fully co-operated with the FCA’s investigation.

“We very much regret the situation that led to this settlement. Barclays has undertaken a significant amount of work to enhance our systems and controls and is committed to the highest standards across all of our operations,” said Antony Jenkins, group chief executive of Barclays.

“While there is much more to do to achieve the deep-rooted cultural change we embarked upon at the start of 2013, Barclays today has significantly changed for the better. We are committed to remain focused on delivering on this agenda, underpinned by our Purpose and Values. These situations strengthen our resolve to improve,” he added.

When banks were punished over a year ago for the interbank interest rate manipulations, this publication asked the World Gold Council, and other organisations involved in the gold industry, whether there could be similar problems with how market prices for the yellow metal were arrived at, but was unable to discover whether there had been offences committed.