shares of quest diagnostics inc dgx inched 014 higher to 14267 thursday on what proved to be an allaround positive trading session for the stock market with the sp 500 index spx rising 133 to 414622 and the dow jones industrial average djia rising 114 to 3402969 quest diagnostics inc closed 1567 short of its 52week high 15834 which the company achieved on december 29th the stock underperformed when compared to some of its competitors thursday as unitedhealth group inc unh rose 097 to 52623