A method for managing an investment vehicle. The investment vehicle issues multiple debt instruments to a plurality of investors. The debt instruments have different liability characteristics. The proceeds of the debt instruments are invested in assets. From time to time, liabilities on the debt instruments and the credit quality of the assets is reevaluated, to ensure that the cash flows generated by the portfolio, disregarding fair market value of the assets, will be sufficient to pay timely principal and interest on the liabilities. In response to the reevaluating, the capital structure of the investment vehicle is adjusted to maintain a desired agency rating for the debt instruments.