Confusing 0.05 and 5% cost hundreds of millions

"Some Risk Model components sent information to the Optimizer in decimals while other components reported information in percentages; therefore the Optimizer had to convert the decimal information to percentages in order to effectively consider all the information on an equal footing. Because proper scaling did not occur, certain decimal information was not converted to percentages and the Optimizer did not give the intended weight to common factor risks."

And the impact: -- AXA Rosenberg had to make clients whole for $217 million in losses, plus pay a $25 million penalty. -- Barr Rosenberg had to pay a $2.5 million penalty and is barred from the securities industry for life. -- AXA Rosenberg's assets under management fell from $70 billion to $29 billion (http://www.nytimes.com/2011/09/23/business/ex-axa-rosenberg-...)