Global ratings agency Standard & Poor's has admitted that the sub-prime crisis in the United States taught it a lesson.

"We've had to change our assumptions regarding the US housing market," said Konrad Reuss, MD of Standard and Poor's in South and sub-Saharan Africa.

"However, our ratings have held up elsewhere and leaving aside debt products related to the US housing market, our ratings continue to remain efficient tools for investors," he said.

Many economic commentators have pointed out that what ratings agencies think is not as important as it used to be, following just how deeply these agencies have been implicated in the current global financial crisis.

The US Securities and Exchange Commission has been studying their actions while the European Union has been contemplating strong new regulations when it comes to ratings agencies.

The agencies have come under fire in the US for their high ratings of mortgage backed securities (MBS) that did not show the financial stability of the borrowers.

However, as Reuss pointed out, the ratings agencies were just once facet of a series of actions that brought about the US's credit crunch.

"But our ratings weren't precise in a number of cases when it came to sub-prime.
"However, this doesn't mean that we are going to change our methodology ... ratings should always be forward looking" he said.

He welcomed regulation. However, he insisted that it had to be sound, globally consistent regulation -- this would restore confidence in the rating process.