Citigroup (NYSE:C) reported fourth-quarter earnings this morning, posting a $7.6 billion loss, or $0.33 per share.

Whenever a bank releases earnings, I like to break the numbers apart and try to find out where the money is coming from. Banks are complex, and often, the headline number doesn't tell the whole story.  

But this is a thorny task when it comes to Citigroup. The company is so large, so complex, and has so many divisions, segments of divisions, and divisions guaranteed by the government, that coherently summarizing its income statement is a joke. Any summary would be several pages long and require chapters of footnotes.

This is why you should keep your distance from big banks. They're just too complicated.

Last year, Citigroup broke itself up into two operating units: Citicorp, the good stuff, and Citi Holdings, the bad stuff. Both fall under the "Citigroup" roof, but the results are still reported separately.

Broken out by this simple segmentation, here's what you get:

Q4 net income by segment

Citicorp

$1.7 billion

Citi Holdings

($2.4 billion)

Corporate/other

(7 billion)

Total

($7.6 billion)

The "corporate/other" category contained a one-time $6.2 billion loss from repaying TARP last quarter. This is the rare occasion where "one-time" is truly that. Backing that charge out, headline earnings would have been a loss of $1.4 billion, or $0.06 per share.

Compared to last year, that isn't bad. But when you consider the spectacular results Goldman Sachs (NYSE:GS), and JPMorgan Chase (NYSE:JPM) have recently achieved thanks to capital markets trading, Citigroup is still clearly well behind its peers.

Digging into the credit quality of Citigroup -- the combined parent company -- might show us why.

Metric

Q4 2009

Q3 2009

Consumer Loans 90+ Days Delinquent  

4.82%

4.37%

Consumer Loans 30-89 Days Delinquent

3.56%

3.65%

Allowance for Losses/ Total Loans

6.09%

5.85%

Nonperforming Assets/ Total Loans

5.44%

5.25%

Allowance for Losses/Nonperforming Loans   

112%

111%

Most credit-quality metrics either weakened slightly or improved at a meaningless rate. Granted, some might interpret that as stabilization, and a sign that credit losses will improve in the year ahead. That could be true, but it's too early to tell definitively. I'll be looking very hard at the loan quality of Wells Fargo (NYSE:WFC) and Bank of America (NYSE:BAC) in the coming days, to see whether Citigroup remains mired in a league of failure all its own.  

What do you think? Share your thoughts in the comment section below.

Fool contributor Morgan Housel doesn't own shares in any of the companies mentioned in this article. The Fool has a disclosure policy.