This excerpt taken from the C 10-Q filed Oct 31, 2008.
Impact on Citigroup's Credit Spreads
As a result of government actions and for other reasons, credit spreads on Citigroup's debt instruments have substantially narrowed since September 30, 2008. Although this may change before the end of the year, if Citigroup's credit spreads are substantially narrower at December 31, 2008 than at September 30, 2008, it could have a meaningful impact on the value of derivative instruments and those liabilities for which the Company has elected the fair value option. See "Derivatives" on page 40 and Note 17 on Fair Value on page 125 for a discussion on the impact of changes in credit spreads in the third quarter.