Denmark's biggest banks are firing Moody's Investors Service as they win assurances from some of the country's biggest investors that the opinions of ratings companies hold limited value.

Nykredit A/S, Denmark's biggest mortgage lender and Europe's largest issuer of covered bonds backed by home loans, terminated its contract with Moody's on April 13, citing its "volatile" views. Danske Bank A/S's mortgage unit Realkredit Danmark A/S, the country's second-largest home-loan provider, dropped Moody's in June. Jyske Bank A/S, Denmark's second-biggest listed bank, is looking into ending its dealings with Moody's, according to Steen Nygaard, its head of treasury.

"They have just crossed the line for fairness," Nygaard said in an interview. "It's not just that we have an opinion and if they rule against us, we are mad and walk away. It is about the fundamentals where we simply cannot follow Moody's arguments."