"For two years Commerzbank either failed to report or reported inaccurately almost all of its reportable transactions," the Financial Services Authority said in a statement.
These breaches took place despite "repeated reminders" to firms of their reporting obligations to the FSA and "specific requests to Commerzbank for the firm to check its data," it said.
The fine, worth €686,000 or $912,000, was reduced by 30 percent because Commerzbank cooperated fully with the investigation, the FSA said, adding that the penalty would otherwise have been £850,000.
The German bank said in a brief statement: "Commerzbank has fully cooperated with the FSA and is deeply committed to meeting its regulatory obligations."
The FSA noted that it was the fifth time since August 2009 that it imposed a fine against a company for failing to provide accurate transaction reports. The agency uses the data to detect and investigate suspected market abuse such as insider trading and market manipulation.
The Labour government created the FSA in 1997 and wants to increase its powers. The Conservative opposition has vowed to eliminate the agency and hand its powers to the Bank of England if they win May 6 general elections.