You'd probably find Harry Markopolous's No One Would Listen interesting. He's a bit of a nut, but he's the one who dobbed Madoff in repeatedly, to no effect, and he goes into great detail about the brokenness which makes this possible. For starters, there is no "revolving door." The salaries for regulatory work make it very much the booby prize on Wall St, and every one doing regulatory work is looking to move out of it. So you get the worst of the industry supposedly regulating what amount to their prospective employers. As a result, Wall St regulation is impeded by laziness, ignorance and incompetence.