IFS Securities, an Atlanta-based broker-dealer, said it suffered "substantial losses" because of what it called unauthorized transactions made by one of its highest-ranking employees, prompting the company to alert federal regulators.
The firm said in a statement to Bloomberg News that it fired the banker, whom it didn't name but described as "one of IFS Securities' most trusted senior employees."
The firm said it also alerted the Securities and Exchange Commission, the Financial Industry Regulatory Authority Inc. and the Federal Bureau of Investigation, and is cooperating with those agencies.
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IFS didn't disclose the nature of the money-losing trades, though it said they didn't involve customers' assets.
The company said it "will be unable to make any detailed public comment concerning recent events, given the complexity of the situation and the existence of ongoing investigations that it understands have commenced."
Judith Burns, a spokeswoman for the SEC, declined to comment. Messages left with spokespeople for the FBI and Finra weren't immediately returned.