Financial Crisis Inquiry Commission report.
While you're unlikely to read it all, you should read the conclusions
We conclude this Financial crisis was avoidable. The crisis was the result of human action and inaction, not of Mother Nature or computer models gone haywire. The captains of Finance and the public stewards of our Financial system ignored warnings and failed to question, understand, and manage evolving risks within a system essential to the well-being of the American public. Theirs was a big miss, not a stumble.
While the business cycle cannot be repealed, a crisis of this magnitude need not have occurred. To paraphrase Shakespeare, the fault lies not in the stars, but in us. Despite the expressed view of many on Wall Street and in Washington that the crisis could not have been foreseen or avoided, there were warning signs. The tragedy was that they were ignored or discounted. There was an explosion in risky subprime lending and securitization, an unsustainable rise in housing prices, widespread reports of egregious and predatory lending practices, dramatic increases in household mortgage debt, and exponential growth in Financial Firms’ trading activities, unregulated derivatives, and short-term “repo” lending markets (see our explanation of repo 105), among many other red lags. Yet there was pervasive permissiveness; little meaningful action was taken to quell the threats in a timely manner.
The prime example is the Federal Reserve’s pivotal failure to stem the low of toxic mortgages, which it could have done by setting prudent mortgage-lending standards.....