Many investors have relied on another fallacy – that rating agencies accurately rate enterprises and securities across different sectors. For much of the 20th century, AA-rated railroad bonds defaulted twice as often as single-B industrials. Recent regulations provided incentives for investment in complex, AAA-rated mortgage-backed securities never close to AAA quality. Ironically, investors will lose more money on AAA credits than on any other rating category.
With results like those, it's a no wonder the rating agencies need government support to sustain their oligopoly.
*Yes, that Michael Milken