I
Installment Loan: An obligation to repay monies borrowed at fixed intervals over time.
 
Institutional Investor: A financial institution such as a mutual fund, insurance company, or pension fund that purchases securities in large quantities.
 
Insurance: Type of guarantee in which any agency pledges the use of accumulated insurance premiums to offset the cost of default on the part of borrowers. "Loan insurance" is considered the equivalent of a "loan guarantee."
 
Intelligent Transportation Systems: The application of advanced electronics and communication technologies to enhance the capacity and efficiency of surface transportation systems, including traveler information, public transportation, and commercial vehicle operations.
 
Interest Method: Method used to amortize the premium or discount of an investment in bonds, or to amortize the subsidy cost allowance of direct loans. Under this method, the amortization amount of the subsidy cost allowance equals the effective interest minus the nominal interest of the direct loans. The effective interest equals the present value of the direct loans times the effective interest rate (the discount rate). The nominal interest equals the nominal amount (face amount) of the direct loans times the stated interest rate (the rate stated in the loan agreements).
 
Interest Subsidy: A subsidy provided by a financial institutions (such as multi-lateral lenders, state infrastructure banks, or export credit agencies)f to lower overall financing costs for project sponsors. With this tool, project sponsors repay loans at less than current market rates. Market rates may be determined by the cost of borrowing through conventional issues of comparable duration.
 
Interest: Sum paid or calculated for the use of capital. Financing interest is the charge assessed as a cost of extending credit as distinguished from additional interest which is the charge assessed on delinquent debts in order to compensate the federal government for the time value of money owed and not paid when due. Additional interest is accrued and assessed from the date of delinquency.
 
Investment Grade: Describes the top four rating categories of relatively secure bonds suitable for a conservative investor. Standard & Poor's rating service looks upon all bonds between the AAA and BBB ratings as investment grade. Generally speaking, any bonds rated below BBB are considered to have speculative features and are deemed sub-investment grade or junk bonds.