NEW YORK (

TheStreet

) -- The

Securities and Exchange Commission

may be investigating another bank's role in a bubble-era derivatives deal, as the agency works to restore its tarnished reputation.

According to a report, the SEC is looking into a $1 billion collateralized debt obligation (CDO) that

Citigroup

(C) - Get Report

created in 2007. The SEC is trying to determine whether Citi "improperly pushed" a third-party to include certain assets, says

ProPublica

. The group highlighted the deal a few months ago as an example of Wall Street's excess in the run-up to the financial crisis.

The SEC similarly investigated a CDO created in 2007 by

Goldman Sachs

(GS) - Get Report

. The regulator filed fraud charges against Goldman in April and settled with the firm for $500 million in July.

When that settlement was announced, the SEC said it was investigating practices at other Wall Street firms with a big presence in structured products. A spokesman didn't immediately respond to a request for comment from

TheStreet

on Thursday.

The SEC has gotten more aggressive about investigating and taking action against big banks this year under Chairman Mary Schapiro. The agency has been harshly criticized for not seizing on obvious fraud cases such as Ponzi schemer Bernie Madoff, as well as other less-than-reputable practices that were widespread up until 2007. At a securities-industry conference this month, Schapiro acknowledged the agency's earlier flaws and said she was working to improve practices and get tougher on big banks.

""We tried to make Madoff a real learning experience for the SEC," she said

at the event on Nov. 8. "It was a real tragedy."

-- Written by Lauren Tara LaCapra in New York

.

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