Citigroup Inc. disclosed a new government probe involving theindustry's trading and clearing of interest-rate swaps five monthsafter paying $425 million to resolve claims that it attempted torig derivatives markets.

The bank is cooperating with the U.S. Commodity Futures TradingCommission, New York-based Citigroup said Monday in a regulatoryfiling. The case is related to a pension fund's 2015 antitrustlawsuit alleging that 12 of the biggest swap dealers blocked fundmanagers from trading the instruments on exchanges to preservetheir profits, according to a person with knowledge of theinvestigation who asked not to be identified because theinformation isn't public.

The disclosure is the latest questioning the role of WallStreet's biggest dealers in helping determine the prices for arange of financial instruments. Authorities around the world havebeen clamping down on the derivatives and currency markets since2013 after allegations that bank traders rigged benchmarks. Inthe currency market, more than a half-dozen lenders have been fineda total of more than $10 billion and scores of traders have beendismissed. Other investigations into gold markets and currencyoptions are also under way.