Did the Gramm-Leach-Bliley Act cause the housing bubble?

No.  That is one common myth among the progressive left.  Because it involves financial deregulation and the unpopular Phil Gramm, the Act is vilified and assumed to be part of a broader chain of evil events.  Here are some of the articles which promulgate the myth that the Act caused or helped cause the housing bubble.  One version of the claim originates with Robert Kuttner, but if you read his article (and the others) you’ll see there’s not much to the charge.  Kuttner doesn’t do more than paint the Act as part of the general trend of allowing financial conflicts of interest. 

Most of all, the Act enabled financial diversification and thus it paved the way for a number of mergers.  Citigroup became what it is today, for instance, because of the Act.  Add Shearson and Primerica to the list.  So far in the crisis times the diversification has done considerably more good than harm.  Most importantly, GLB made it possible for JP Morgan to buy Bear Stearns
and for Bank of America to buy Merrill Lynch.  It’s why Wachovia can consider a bid for Morgan Stanley.  Wince all you want, but the reality is that we all owe a big thanks to Phil Gramm and others for pushing this legislation.  Brad DeLong recognizes this and hail to him.  Megan McArdle also exonerates the repeal of Glass-Steagall. 

Here is a good critique of GLB, on the grounds that it may extend "too big to fail" to too many institutions.  That may yet happen but not so far.   

The Act had other provisions concerning financial privacy.

Maybe you can blame some conflict of interest problems at Citigroup and Smith Barney on the Act.  But again that’s not the mortgage crisis or the housing bubble and furthermore those problems have been minor in scale.  Ex-worker has a very sensible comment.  The most irresponsible financial firms were not, in general, owned by commercial banks.  Here’s lots of informed detail on GLB and the bank failure process.  Here is another good article on how GLB didn’t actually change Glass-Steagall that much.

Here’s a Paul Krugman post on GLB; he attacks Phil Gramm but he doesn’t explain the mechanism by which GLB did so much harm.  The linked article has no punch on this score either, although you will learn that Barack Obama has scapegoated GLB, again without a good story much less a true story. 

I may soon cover the Commodity Futures Modernization Act as well.