Operating funds are used primarily to fund UT System institutions' short-term operating needs as well as long-term institutional needs associated with capital programs, financial reserves, and endowment matching funds. The UT System institutions have three investment fund options, allowing the institutions to match the particular time horizon of their operating funds with the time horizon of each investment fund. The three funds are the Short Term Fund (STF), the Short Intermediate Term Fund (SITF) and the Institutional Index Funds (IIF). The IIF consist of a U.S. debt index fund and a U.S. equity index fund and are designed to offer higher expected returns than those available with the STF and SITF. As of August 31, 2005, operating funds of UT System institutions amounted to $3,776.4 million.