this is long-winded, decade old post discussing some of the issues ... including discussion of citi nearly went under two decades ago because of ARMs and not adequately understanding what happens when interest rates adjust.
http://www.garlic.com/~lynn/aepay3.htm#riskm

I believe that some of the people involved in that analysis were part of forming a leading risk analysis (software) company in 1990.

Playing long/short mismatch has been known for centuries to bring down institutions. They (and others) have commented that Bear-Stearns and Lehman had marginal chance of surviving playing long/short mismatch ... this discusses long/short mismatch and some number of other related issues:
http://www.forbes.com/entrepreneursfinance/2007/11/13/citigroup-suntrust-siv-ent-fin-cx_bh_1113hamiltonmatch.html
decade old article from the fed
http://www.frbsf.org/econrsrch/wklyltr/2000/el2000-26.html

Playing long/short mismatch was independent of heavy leveraging, SIVs, and whether or not the toxic (subprime) CDOs deserved their triple-A ratings.

a couple recent, related archived (linkedin) discussions:
http://www.garlic.com/~lynn/2009.html#79 The Credit Crunch: Why it happened?
http://www.garlic.com/~lynn/2009.html#80 Are reckless risks a natural fallout of "excessive" executive compensation?
http://www.garlic.com/~lynn/2009.html#84 what was the idea behind Citigroup's splitting up into two different divisions?
http://www.garlic.com/~lynn/2009b.html#1 Are Both The U.S. & UK on the brink of debt disaster?
http://www.garlic.com/~lynn/2009b.html#8 Do emperos from the banks have new clothes?

It was actually Fredric who wrote the "blurb", but I'm happy to take credit :-)