Moody's, Standard & Poors and Fitch stood by their AAA top ratings for Collateralized Debt Obligations (CDOs), which are based in part on pools of subprime mortgages. Some of that stuff was indeed top drawer, but the bottom tranches were filled with junk. So how do you make the call? The agencies, looking backward at the accumulated data, continued to give their top rating to securities that were piling up risk as each week went by and the real estate markets started to wobble. And did we mention that the agencies get paid by the issuers of the CDOs to make their supposedly objective rating? When it all went south — propelled in part by the same folks, who suddenly started slapping bad grades on already fragile firms like AIG — the agencies said their ratings were merely opinions. In our opinion, they're useless.