The U.S. Justice Department is investigating the credit-default swaps (CDS) market, Bloomberg said, citing market data provider Markit Group Ltd.

"Markit has been informed of an investigation by the Department of Justice into the credit-derivatives and related markets," the news agency cited Markit spokeswoman Teresa Chick as saying yesterday in an e-mailed statement.

Chick declined to comment to the news agency on the nature of the investigation.

Markit and the Justice Department could not be immediately reached for comment by Reuters.

The CDS market involves guarantees bought by bond investors to protect themselves against defaults. CDS are over-the-counter contracts between two counterparties that bet on whether a company will default on its bonds within a fixed period of time.