The publisher of the Daily Mail newspaper said a downturn in the print advertising market was squeezing margins in its media business.
This resulted in an 11% drop in first-half profit and a lower outlook for the year.
Daily Mail and General Trust said the operating margin for its media business would be about 10% for the year, rather than remaining at last year's 13%.
It said the outlook for the full year was now adjusted for the change in guidance to the operating margin.
The company said print advertising revenues in the six months to the end of March declined by £18m, with the market deteriorating further in the second quarter.
Digital advertising grew strongly, but was not enough to close the gap, the company said.
The group reported pretax profit for the period of £129m.