Credit rating agencies are businesses that seek to maximise profit by assessing the risks of financial assets – primarily traded stocks, and the bonds (debt) of companies and governments. Despite the alarming and lamentable fact their very business model is based on a conflict of interest – they are paid by the issuers of stocks and bonds, rather than by investors – they command credibility.

They do not merit such trust. They should be seen as but one source of information investors might look to in doing due diligence before buying a financial instrument. And they should be seen as dangerously fallible; their assessments are merely opinions. The credit rating business is a cosy oligopoly; it's dominated by three firms, Moody's, Standard and Poor's and Fitch. Their record is arguably catastrophic. They completely missed one of the biggest corporate collapses in history, Enron. They over-reacted to the European Union's fiscal and debt woes, helping worsen the situation by spooking investors.

But their biggest blot is that they played a huge role in sparking the global financial and economic crisis – which started almost 10 years ago and is still hurting many nations – by giving glowing ratings to mortgage-backed investments that were bound to collapse. Their egregious and disgraceful complicity in a disaster that caused untold harm to so many citizens around the world is forensically and compellingly documented in Michael Lewis' book The Big Short. If you still believe a tick from the agencies should be "coveted", this book will probably change your view.

In 2010, the US government tightened up financial market regulation, including the requirement on the ratings agencies. But as many, including Professor John Ryan of the University of Cambridge, have pointed out, there is a glaring need to go further. Unlike the assessments of independent central banks, which have far greater credibility and competence than ratings agencies, the agencies' deliberations are not transparent.

Here's part of Professor Ryan's critique: "First there is a need to rank the CRAs in terms of performance, in particular the accuracy of their ratings. Second, there is a need to facilitate the ability of investors to hold CRAs accountable in civil lawsuits for inflated credit ratings, when a CRA knowingly or recklessly fails to conduct a reasonable investigation of the rated security. Third, there is a need to ensure CRAs institute internal controls, credit rating methodologies, and employee conflict of interest safeguards that advance rating accuracy. Fourth, regulators should use their inspection, examination, and regulatory authority to ensure CRAs assign higher risk to financial instruments whose performance cannot be reliably predicted due to their novelty or complexity."