By Dan Wilchins

NEW YORK, May 13 (Reuters) – New York Attorney General Andrew Cuomo is looking at whether investment banks duped credit rating agencies, but a bigger question is why the rating agencies failed to prevent the financial meltdown.

Banks may indeed have misled Moody’s Investors Service, Standard & Poor’s, and Fitch into giving higher ratings than some securities really merited, but rating agencies should have done more to avoid being fooled, critics said.

Until the structural problems with rating agencies are fixed, new credit bubbles will likely be inflated.

Those problems may be closer to getting fixed. The U.S. Senate voted on Thursday to impose tighter regulations on credit rating agencies, taking steps including letting regulators decide which agency will assign ratings to an issuer.

That Senate proposal follows years of hearings into problems at rating agencies, which essentially assign grades to bonds to help investors evaluate the securities.