Caesars in September had agreed to buy the gambling group for 2.9 billion pounds ($3.82 billion) to expand in the fast-growing U.S. sports-betting market, after beating out Apollo.
The possibility of Apollo firming up its bid faded after Caesars made it clear it could terminate the deal, if William Hill decided to proceed with another offer from rival parties mentioned in a list set by Caesars.
However, Apollo has said the decision to not make an offer for the entire company does not affect its other plans, referring to its intention to buy William Hill's UK assets.
Sources had told Reuters in September that Caesars could sell William Hill's UK assets to Apollo as part of its deal, under which it seeks to sell the bookmaker's non-U.S. operations.
(Reporting by Pushkala Aripaka in Bengaluru; editing by Uttaresh.V)