When the British Financial Stability Board was established a couple of years ago, it declared that one of its goals was to produce better "early warning" systems of looming financial trouble spots. Now it is turning this rhetoric into reality. Investors should pay attention.

Last month, the FSB issued a small advisory report entitled: "Potential financial stability issues arising from recent trends in exchange-traded funds". Unsurprisingly, this did not cause a storm.  After all, ETFs seem as dull as ditchwater to most politicians; almost as boring as the world of collateralized debt obligations looked before 2007.