Citigroup Global Markets Ltd. has been sanctioned by the U.K. Financial Conduct Authority (FCA) for failing to adequately bolster it defences against insider trading and market manipulation.

The FCA fined the firm £12.6 million, after finding that it failed to ensure that its trade surveillance capabilities met tougher requirements that were introduced in 2016 regarding firms’ ability to detect and report abusive trading.

As a result, “Citigroup Global Markets could not effectively monitor its trading activities for certain types of insider dealing and market manipulation,” the regulator said.

The regulator found that the firm took 18 months to identify and assess its specific market abuse risks. In turn, these shortcomings resulted in “significant gaps” in its trade surveillance procedures, the FCA said.

“The framework for market integrity depends on the partnership between the FCA and market participants using data to detect suspicious trading. By not fully implementing the new provisions when required, Citigroup Global Markets did not carry its full weight in this partnership, impacting market integrity and the overall detection of market abuse,” said Mark Steward, executive director of enforcement and market oversight at the FCA, in a statement.

The FCA said that Citigroup Global Markets agreed to resolve this case and qualified for a 30% discount on its penalty. Without the discount, it would have been fined £17.9 million.