The £13,285,900 fine comes after the company incorrectly reported over 35 million transactions between November 2007 and November 2014.
The regulator said the size of the fine reflects the severity of the company’s misconduct, and its failure to address the root causes of the breaches despite a private waning in 2002 and a £150,000 fine in 2006.
It has used a penalty of £1.50 per line of incorrect or non-reported data for the first time, an increase on the £1 per line used in the three most recent transaction reporting cases.
MLI agreed to settle at an early stage of the investigation and received a 30% reduction in their overall fine.
Director of enforcement and market oversight at the FCA, Georgina Philippou, said: “Proper transaction reporting really matters. MRI has failed to get this right again, despite a private warning, a previous fine, and extensive FCA guidance and enforcement action in this area.
“The size of the fine sends a clear message that we expect to be heard and understood across the industry.
“Accurate and timely reporting of transaction is crucial for us to perform effective surveillance for insider trading and market manipulation in support of our objective to ensure that markets work well and with integrity.”
