The upgrade to positive from negative reflects what the credit rating agency called the "potentially positive impact" of the merger on Carlton's credit worthiness.
Carlton was up 1.34% this morning to 135.75p, while Granada was up 0.66% to 76.25p.
Moody's said that the upgrade was dependent on the merger being completed as planned, and would be subject to Carlton's performance and debt protection measurements.
The merger still has to be approved by shareholders, the Competition Commission and the Independent Television Commission.
Carlton and Granada agreed the terms of the merger yesterday, following a statement issued to the City last week that the two were in advanced talks.
If regulatory clearances are obtained before the government's communications bill gets on to the statute books, the two ITV companies have said they intend to carry out the merger in two stages to get round current regulatory obstacles.
They also have to deal with the contentious issue of airtime sales, and the domination of the market by the two broadcasters' own sales houses.
A management buyout by Carlton sales chief Martin Bowley has been touted as a likely solution to the airtime sales issue, which should placate advertisers.
Carlton and Granada are promising that the merger will lead to cost savings of around £35m a year in duplicated infrastructure and administration in broadcasting, content and central services and a further £20m in savings is achievable on full merger. However, there will be a one-off cost to achieve these benefits, estimated to be £40m.
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