** British bank's U.S.-listed shares down 5 percentat $14.94 premarket after New York state attorney general filessecurities fraud suit against it
** Attorney general accuses the bank of giving an unfairedge in the United States to high-frequency trading clients
** Action the highest-profile case yet to emerge in U.S.authorities' efforts to ensure that dealers are not ripping offinvestors in increasingly automated stock markets