Question: When authorities could no longer calculate the risks of complex financial innovation products, who did they rely on for information?
Sentence: As financial assets became more and more complex, and harder and harder to value, investors were reassured by the fact that both the international bond rating agencies and bank regulators, who came to rely on them, accepted as valid some complex mathematical models which theoretically showed the risks were much smaller than they actually proved to be.
Answer in sentence: no