Citigroup, Inc. (C) is facing a slide into oblivion, if Thursday's historic slide in stock price is any indication: shares in the once most-valuable bank by both market cap and assets slipped below the $1 mark during morning trading, and were last seen hovering at $1.03, off 8.85 percent, when this story was published. The New York-based bank has seen more than 85 percent of its market value disappear this year as investors came to grips with a mountain of bad mortgage and related other bad debt, that has pushed the troubled bank into needing some of the Federal government's largest amount of financial assistance. It's also pushed the bank towards the precipice of outright failure, according to various key analysts. Traditionally, if a company's shares trade below the $1 mark for more than 30 days, the NYSE puts the company on notice for potential delisting. That won't happen here, since the exchange recently modified its rules, suspending the $1 rule amid what it called a "current period of unusual market volatility and decline," according to a press statement. And just how far has the former banking giant fallen? Consider that in Jan. 2007, market cap at Citi was just north of $270 billion; it's now $5.61 billion. Read that again. Citigroup reported a net loss of $8.29 billion, $1.72 per share, for the fourth quarter of 2008, and an $18.72 billion, or $3.88 billion per share, net loss for all of 2008. It has also split into two parts: Citicorp and Citi Holdings, with Citi Holdings taking on many of the bank's riskier assets. The company is scheduled to report its first quarter earnings in April. Write to Paul Jackson at paul.jackson@housingwire.com. Disclosure: The author held no relevant investment positions when this story was published. Indirect holdings may exist via mutual fund investments. HW reporters and writers follow a strict disclosure policy, the first in the mortgage trade.