The harsh light of the Libor rate-fixing scandal has crossed the Atlantic, with both Citigroup and JPMorgan Chase saying regulators and investigators have requested information from them in a so-far preliminary probe of the case.
Share prices for both -- as well as Bank of America, which has not said if it was asked for information -- have fallen sharply this week amid worries they could be in line for the type of heavy fines laid on Britain's Barclays Bank, at the center of the scandal.
Barclays has been fined $452 million (360 million euros) by British and US regulators for attempted manipulation of the markets for Libor and Eurobor benchmark interest rates between 2005 and 2009.
Three top Barclays executives have resigned and on Friday Britain's Serious Fraud Office said it would formally investigate the case, which has dented London's reputation as a top financial center.
But speculation runs to other banks because the Libor rate is set based on information from 16 international banks, and many think that manipulating it would take more than one bank.
The issue affects not just banks but commercial and retail borrowers around the world -- in the United States, the payments of a floating rate home mortgage loan are often tied to the Libor base rate.
Citi, JPMorgan and Bank of America are three of the 16 banks that fix the rate, as an average of what they say they pay for funds in London's interbank market.
All three have declined to comment on the scandal.
But JPMorgan and Citi have said that they had received requests for information from regulators and were cooperating.
Citigroup noted in its reports that the Japanese Financial Services Agency, among several regulators involved in the cross-border investigations, had taken administrative action against its Citigroup Global Markets Japan unit over "certain communications" made by two CGMJ traders about Libor and the Euroyen Tokyo interbank rate, or Tibor.
The unit was given a two-week suspension from trading in yen-linked derivatives in January.
JFSA also took administrative action against Citibank Japan in part related to the handling of the communications made by the CGMJ traders.
"The inquiries by government agencies into various interbank offered rates are ongoing," the bank said in a report to the Securities and Exchange Commission.
Citigroup and JPMorgan also acknowledged private civil and class-action lawsuits filed against the Libor-setting banks beginning in April over the issue.
The suits have been assembled together into one action proceeding in the New York federal district court.
Even if there is not yet any formal investigation of the US banks over the Libor rate manipulation, their shares have already taken falls over worries they could be involved.
JPMorgan shares were off 5.1 percent for the week in afternoon trade Friday; Citi shares were down 4.4 percent and Bank of America 6.5 percent.