institutional investors, who have access to sophisticated risk management resources such as hedge funds, private equity firms and units of investment banks. Firms that specialize in investing in distressed debt are often referred to as vulture funds. See . Investors in distressed securities often try to influence the process by which the issuer restructures its debt, narrows its focus, or implements a plan to turn around its operations. Investors may also invest new capital into a distressed company in the form of debt or equity. According to a 2006 report by Edward Altman, a professor of finance at the NYU Stern School of Business, distressed debt investments earned well above average returns in 2006 and there were more than 170 institutional distressed debt investors. These institutions used "very strong and varied strategies including the traditional passive buy-and-hold and arbitrage plays, direct lending to distressed companies, active-control elements, foreign investing, emerging equity purchases and equity plays during the reorganization of a firm in bankruptcy". The most common distressed securities are bonds and bank debt. While there is no precise definition, fixed-income instruments with a yield to maturity in excess of 1,000 basis points over the risk-free rate of return (e.g., Treasuries) are commonly thought of as being distressed. Distressed securities often carry ratings of CCC or below from agencies such as Standard & Poor's, Moody's and Fitch. Risk management By 2006, the increased popularity in distressed debt hedge funds led to an increase in the number of benchmark performance indexes. Highly specialized risk analysts and experts in credit are key to the success of alternative investments such as distressed debt investment. They depend on accurate market data from institutions such as CDX High Yield Index and India-based Gravitas, which combines risk management software with sophisticated risk analysis using advanced analytics and modeling. They produce customized scenarios that assess the risk impact of market events. Gravitas uses IBM Risk Analytics technology (formerly Algorithmics), which is also used by major banks, to help hedge funds meet regulatory requirements and optimize investment decisions. When companies enter a period of financial distress, the original holders often sell the debt or equity securities of the issuer to a new set of buyers. Private investment partnerships such as hedge funds have been the largest buyers of distressed securities. By 2006, hedge funds have purchased more than 25% of the high-yield market's supply to supplement their more traditional