Moody’s, S&P Duel Over Meaning of Notching Study, But Nomura Suggests it May Not Matter Significant variation exists in the ratings that are given to asset securitization classes, but the significance of the findings of a recent report depends a lot on whom you ask. Conducted by NERA Economic Consulting and paid for by Moody’s Investors Service, a report on differences in ABS ratings among different rating agencies is adding more fire to the debate