Ira Leon Rennert (born 1934) is an American investor and businessman. Using junk bonds to finance his acquisitions of companies, often in bankruptcy, Rennert has amassed significant holdings in basic, cyclical industries, such as mining and metals, including lead smelters, coal mines, magnesium producers and vehicle assembly lines. Today he controls one of the nation's largest privately held industrial empires, and his personal fortune is estimated to be $5.9 billion.