that back commercial paper or are used for general corporate purposes or, in some cases, acquisitions. For leveraged loans, considered non-investment grade risk, U.S. and European banks typically provide the revolving credits, letters of credit (L/Cs), and — although they are becoming increasingly less common — fully amortizing term loans known as "Term Loan A" under a syndicated loan agreement while institutions provide the partially amortizing term loans known a "Term Loan B". Finance companies have consistently represented less than 10% of the leveraged loan market, and tend to play in smaller deals — $25–200 million. These investors often seek asset-based loans that carry wide spreads and that often feature time-intensive collateral monitoring. Institutional investors in the loan market are principally structured vehicles known as collateralized loan obligations (CLO) and loan participation mutual funds (known as "prime funds" because they were originally pitched to investors as a money-market-like fund that would approximate the prime rate) also play a large role. Although U.S. prime funds do make allocations to the European loan market, there is no European version of prime funds because European regulatory bodies, such as the Financial Services Authority (FSA) in the U.K., have not approved loans for retail investors. In addition, hedge funds, high-yield bond funds, pension funds, insurance companies, and other proprietary investors do participate opportunistically in loans. Typically, however, they invest principally in wide-margin loans (referred to by some players as "high-octane" loans), with spreads of 500 basis points or higher over the base rate. CLOs are special-purpose vehicles set up to hold and manage pools of leveraged loans. The special-purpose vehicle is financed with several tranches of debt (typically a ‘AAA’ rated tranche, a ‘AA’ tranche, a ‘BBB’ tranche, and a mezzanine tranche with a non-investment grade rating) that have rights to the collateral and payment stream in descending order. In addition, there is an equity tranche, but the equity tranche is usually not rated. CLOs are created as arbitrage vehicles that generate equity returns through leverage, by issuing debt 10 to 11 times their equity contribution. There are also market-value CLOs that are less leveraged — typically three to five times — and allow managers more flexibility than more tightly structured arbitrage deals. CLOs are usually rated by two of the three major ratings agencies and impose a series of covenant tests on collateral managers, including minimum rating, industry diversification, and maximum default basket.