Host Ira Glass talks with Michael Perrino, a law professor at St Johns University School of Law in New York, who's writing a book about Ferdinand Pecora called The Hellhound of Wall Street.  Pecora was the lead attorney in the Senate Banking Committee hearings in the 1930s looking into wrongdoing in the banking industry.  When he got the job, he turned the hearings from an unimportant and not terrible useful exercise into a real investigation into Wall Street and the causes of the 1929 stock market collapse.  It spurred Congress to pass landmark reforms regulating Wall Street. Ira and Perrino talk about whether these kinds of hearings could or should happen today. (9 minutes) 

Act One. Investigation Report #1.

Planet Money reporter Chana Joffe-Walt asks a simple question: who was the federal regulator who was supposed to be regulating AIG?  The answer turns out to be far from simple. (21 minutes)

Act Two. Investigation Report #2.

Alex Blumberg and NPR correspondent (and "Planet Money" reporter) Dave Kestenbaum examine what went wrong with the credit ratings agencies.  When all these financial instruments that brought down our economy—the mortgage backed securities, the derivatives—were originally issued, the rating agencies (Standard and Poors, Moody's and Fitch) gave many of these things their top rating of triple-A. Because of the great ratings, trillions were invested. And then the ratings turned out to be wrong. What happened? (24 minutes)