U.S. regulators sanctioned Citigroup Inc. for excessive markups on bond trades, and issued a warning to broker-dealers about fulfilling their due diligence obligations in underwriting municipal bond issues.

The Financial Industry Regulatory Authority announced that it has fined Citi International Financial Services LLC, a subsidiary of Citigroup, US$600,000, and ordered more than US$648,000 in restitution and interest to more than 3,600 customers, for charging excessive markups and markdowns on corporate and agency bond transactions, and for related supervisory violations. It was also ordered to revise its written supervisory procedures regarding its review of markups and markdowns, and best execution in fixed income transactions. In concluding the settlement, the firm neither admitted nor denied the charges.

FINRA found that from July 2007 through September 2010, Citi International charged markups and markdowns of between 2.73% and over 10%, which it says were excessive given market conditions, the cost of executing the transactions and the value of the services rendered. It also says that from April to June 2009, the firm failed to use reasonable diligence to buy or sell corporate bonds so that the resulting price to its customers was as favourable as possible. And, that the firm’s supervisory system regarding fixed income transactions contained significant deficiencies.

Separately, the U.S. Securities and Exchange Commission issued an investor bulletin to help educate investors about municipal bonds, and a new alert concerning compliance measures, to help broker-dealers fulfill their due-diligence duties when underwriting offerings of municipal securities.

The investor alert, issued by the SEC’s Office of Investor Education and Advocacy, explains municipal bonds, including investment risks, and provides information to investors on where they can obtain additional data on particular bonds.

The alert for firms, issued by the SEC’s Office of Compliance Inspections and Examinations, spells out regulators’ concerns about the extent of written documentation by broker-dealers of their due diligence efforts, and their supervision of municipal securities offerings; and it details practices firms can use to properly document their due diligence and supervisory reviews.