shares of marketaxess holdings inc mktx slipped 643 to 29856 wednesday on what proved to be an allaround dismal trading session for the stock market with the sp 500 index spx falling 070 to 409075 and dow jones industrial average djia falling 080 to 3341424 marketaxess holdings inc closed 10122 short of its 52week high 39978 which the company reached on april 4th