Reuters reports that Citigroup (NYSE: C) is poised to announce today the sale of $400 billion worth of assets -- that's 18% of the total. We'll need to wait to find out which assets it plans to sell and how much of a loss (or profit) Citi will take when it sells them. But the New York Times reports the company's deciding based on industry growth trends, market positions, geographic growth rates, business plans and financial results.

I worked for a global bank during a credit contraction and part of my job was to figure out which assets to sell. From that experience, I know that Citi's challenge is to find assets that don't fit with Citi but are worth more to another owner. That's because often the assets that make the most sense to sell strategically are the ones that nobody else wants to own. And the ones that make the most sense to keep are the ones that could generate the biggest profit, if sold. Citi's challenge is to sell the $400 billion worth of assets that make strategic sense to sell and will fetch an attractive price. In today's market, that is a challenge.

So what Citi assets could be on the block? Reuters notes that Citi's U.S. student loan business may make sense to sell, after recent legislative changes and turmoil in the securitization market have made it less profitable. Citi may sell Primerica, a consumer sales network for life insurance and investments. And Citi should sell assets on its trading books, which have contributed to much of the $45 billion write-downs that Citi has taken so far.