AOL Time Warner said it invested substantial additional financial resources in its news network CNN, publishing division Time and America Online as a result of the attacks.
It expects revenue growth of between 5% and 7% or about $38.3bn (£26.2bn) compared with earlier targets of 12% growth or $40bn (£27.4bn). Ebitda is expected to rise 20% to $10.1bn (£6.9bn), as opposed to earlier expectations of $11bn (£7.5bn).
Shares in AOL climbed 9.8% yesterday on Wall Street to $32.50(£22.24).
AOL had been aggressively pursuing steep financial targets agreed last year when the two companies merged. Gerald Levin, chief executive, said, "No financial impact can compare to the terrible suffering and loss of life inflicted by the vicious attacks."
AOL Time Warner's announcement follows a similar warning last week from Viacom, owner of the CBS television network.
Many advertisers cancelled advertising in the weeks after the disaster, which they deemed inappropriate given the circumstances. The TV networks also rearranged schedules giving blanket coverage to the event, without showing any advertising.
Wall Street has since revised profit forecasts for several large media groups.
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