The Commodity Futures Trading Commission has issued subpoenas toICAP Plc brokers and as many as 15 Wall Street banks as part of aninvestigation into possible price manipulation of benchmarkinterest-rate swaps, according to people familiar with thematter.

The CFTC plans to interview about a dozen current and formerbrokers at ICAP's Jersey City, New Jersey, office as well asdealers that contribute prices used to set the daily ISDAfix swaprates, said three of the people, who asked not to be named becausethe matter is private. The regulator is probing whether ICAPbrokers are colluding with dealers who stand to profit frominaccurate quotes, including failing to update published marketprices after trades occur, one of the people said.

The ISDAfix levels, which the Federal Reserve includes in adaily report on money-market rates, are used by everyone fromcorporate treasurers to money managers to determine borrowing costsand to value much of the $379 trillion of outstanding interest-rateswaps globally.