U.S. criminal authorities are probing whether Corey Ribotsky, Managing Member of NIR Group, a Roslyn, N.Y., hedge-fund, defrauded investors about their returns and the holdings of his various funds, The Wall Street Journal reported.

According to the paper prosecutors from the Securities and Exchange Commission, FBI and the U.S. attorney's office in Brooklyn are looking at whether Mr. Ribotsky lied to investors as stock prices fell during the credit crisis.

It said the authorities have not accused Mr. Ribotsky of wrongdoing.

NIR has â?¬430m under management, according to our data.