A managed investment vehicle that holds mainly highly rated asset-backed securities and funds itself using the short-term commercial paper market as well as the medium-term note (MTN) market. Because of the rolling nature of its funding, an SIV is highly dependent on maintaining the highest possible short-term and long-term credit ratings. SIVs differ from cash CDOs of asset-backed securities in that their portfolios are marked-to-market, with their ratings based on capital models agreed with the rating agencies. SIVs also have simpler capital structures than CDOs, usually comprising a junior tranche of capital notes beneath a block of senior liabilities with the same seniority. They have smaller liquidity facilities than commercial-paper conduits - which also invest in high grade ABS. SIV managers include both commercial banks such as Citigroup and Bank of Montreal, and investment managers such as Gordian Knot.