Not sure what your keys are but maybe

SELECT     MSE_SEC_ID, MSE_TCKR_SYMB, MSE_SEC_SHT_NM, MSE_SEC_LNG_NM
FROM         MSECURTY INNER JOIN
                     tblLineUpItems ON MSECURTY.MSE_SEC_ID = tblLineUpItems.SecID
ORDER BY tblLineUpItems.Position


?