Citi's a Tough Sell

Updated from 1:29 p.m. EST

Citigroup (C Quote) shares plummeted 20% Friday, as the ailing bank mulled the sale of all or parts of its businesses.

Citi shares on Friday fell as low as $3.05, a 52-week low, before closing down 94 cents to $3.77 amid a nearly 500-point rally in the Dow Jones Industrial Average. The market capitalization of what was, just a few months ago, the world's largest bank fell to less than $20 billion at its nadir. Not only is that less than the $25 billion preferred equity investment the government last month, but its far less than Citi's $657 billion in deposits, according to its most recent quarterly filing with the Securities and Exchange Commission.

With the stock price and market cap so low, Citi is going to need to act soon, but selling businesses may not be so easy in a public marketplace that is assigning virtually no value to the ailing company ...