The Securities and Exchange Commission is reportedly investigating a complex $1 billion investment deal Citigroup Inc. arranged leading up to the financial crisis.

Citing unnamed sources, online news organization ProPublica said Thursday that the SEC is looking into whether Citi improperly persuaded an independent manager to put certain assets into the deal, a collateralized debt obligation known as Class V Funding III. The CDO, completed in February 2007, was made up of pieces of other CDOs that were backed by risky pieces of subprime mortgages. Citigroup arranged and marketed the deal, while a division of Credit Suisse managed it, ProPublica said. Independent managers like Credit Suisse were in charge of placing the best assets into the CDO.

The SEC has been conducting a much larger investigation into whether Wall Street investment banks duped investors by marketing CDOs they knew contained souring assets before the financial crisis.

Citi issued a statement saying, "it's been widely reported that there are ongoing industry-wide investigations into CDO-related matters, and we do not comment on pending investigations."