To my knowledge, this is the best work done so far on the financial crises of 2007-09, which peaked in September 2008 when, days after Fannie Mae and Freddie Mac were placed in conservatorship by the Treasury Secretary, several of the nation's largest financial institutions became insolvent and either were sold at fire sale prices to healthier banks or went bankrupt.
I have read numerous books on the subject, and reviewed several of them on Amazon, including reviews of the Financial Crisis Inquiry Commission's report, A Colossal Failure of Common Sense, The Big Short, and Too Big to Fail. I have done my own research in primary materials published by the Fed, the GSE's, and dozens of papers published by regional Fed employees and academics around the world and hundreds of blog posts from bloggers of all political perspectives.
This is the best work I have seen. It is concise - in fact, probably too concise - and accurate. It focuses on the heart of the problem, namely the way in which several bipartisanly enacted Federal policies of promoting home ownership turned Fannie and Freddie into "Federal Frankensteins" -- giant, severely undercapitalized, voracious consumers of credit risk that were, by dint of their size and also of biases built into the capital regulations for banks and other financial institutions, so deeply embedded into global financial system that they accounted by themselves for one-sixth of all "systemic risk" in not just the nation but the world.
While focused on Fannie and Freddie, this is not the simple "Community Reinvestment Act" screed that a few have pounded the drum for, and it even goes beyond the intensive credit risk analysis of Ed Pinto and Peter Wallison that has been well publicized. It emphasizes the leverage / undercapitalization of Fannie and Freddie relative to the credit risk, and also explains - not as much as I would have liked - the way in which rules regarding the capital of banks and other financial institutions subsidized demand for ever more Fannie and Freddie paper and thus incentivized their ever deeper push into weaker and weaker credits, to the point where they had subprime exposure - just subprime - equal to 6 times their capital when they went under.
For those who do not find this account persuasive, I will end by quoting one fact that the authors strangely do not use but which I find to be the strongest support for the view that the 1995 policy changes are the wellspring of the crisis; it comes from the Fed's Flow of Funds reports. From 1986 to 1995, the annual growth in US residential mortgage debt averaged less than $200 billion per year; considering inflation and population growth, the rate of growth relative to demand declined significantly over that period. In 1995, when mortgage growth was only $150 billion, the then administration launched its "National Homeownership Strategy" to expand home ownership in which F & F financing played a major role. By 1998, mortgage growth more than doubled, past $300 billion; by 2001 it was over $500 billion, and in 2005, it exceeded $1 trillion. In other words, annual mortgage growth went up more than 600% in that decade. The authors show how most of that was backed by or was held by F & F and how F & F backed or held, in most years, large segments of the subprime volume. This is the best account of how that was a not exclusive, but certainly principal, cause of the financial crises of 2007-09.