6. The Wall Street Joumal reported that the spread on a bond issued by Citigroup changed by 50 basis points (100 basis points = 1%) during trading on December 7. a. The Citigroup bond was included on the list of bonds having "spreads that tightened the most". In general, what would cause a bond's spread to tighten? Use no more than 20 words. b. Explain how the tightening of a bond's spread would affect the bond's value. Use no more than 20 words. 1