Adds deal details, company comment, background in paragraphs 2-5

COPENHAGEN, Nov 3 (Reuters) - Denmark's Orsted ORSTED.CO said on Monday it agreed to sell a 50% stake in Britain's Hornsea 3 offshore wind farm for 39 billion Danish crowns ($6.09 billion), widely regarded as a crucial move to prevent a crippling credit rating downgrade.

Orsted, the world's largest offshore wind developer, seeks to restore investor confidence as it faces rising costs from supply chain disruptions and inflation, as well as uncertainty wrought by U.S. President Donald Trump's opposition to renewable energy.

The company said in a statement it sold the stake in the 8.5 billion pound ($11.41 billion) project to New York-listed Apollo Global Management APO.N, which manages more than $800 billion in assets, leaving Orsted with 50% ownership.

"The transaction represents a key milestone in Orsted's funding plan and balances the key objectives for partnerships and divestments with an emphasis on capital management," Orsted said in a statement.

Orsted in October raised $9.4 billion through a heavily discounted rights issue to shore up its balance sheet, and later announced it would cut about a quarter of its workforce by the end of 2027.

($1 = 0.7451 pounds)

(1 Danish crown = 0.1164 pounds)

(Reporting by Louise Breusch Rasmussen and Gwladys Fouche; editing by Terje Solsvik and Bill Berkrot)

((Louisebreusch.rasmussen@tr.com; +45 21 27 97 79;))