In the aftermath of the financial crisis, American taxpayers poured $187.5 billion into two huge but poorly understood companies: Freddie Mac and Fannie Mae.

Now controlled by the government, the companies play an even larger role in the economy than they did before the crisis and their bailout, but they are riven by conflicts of interest and clashing goals. Are they private companies, only out to increase their profits, or are they instruments of government policy, dedicated to keeping home ownership available?

ProPublica has focused on the tensions within Freddie Mac and Fannie Mae, as well as those besetting their regulator, the Federal Housing Finance Agency.