NEW YORK -- Citigroup ( C) says it will acquire the remaining $17.4 billion in assets held by structured investment vehicles it already supports. The transaction announced Wednesday will help Citi fully unwind the troubled SIVs, and allows the funds to fully repay maturing debt obligations. Citi will move the SIV assets to a portfolio of assets held for sale. The value of SIV holdings has fallen sharply during the ongoing credit crisis, forcing banks that operated them to provide additional financial support. An SIV is a fund that borrows money by issuing short-term securities at a low interest rate and then lends that money by purchasing long-term securities at higher interest. Investors can profit from the difference in rates.