Though the subprime mortgage business is in a serious crisis as loan volume is plummeting, defaults are rising and some of the biggest lenders have cut back or shut down, private equity, hedge funds and investment banks are seeing opportunity amid the wreckage, the New York Times reported today. In many parts of the country, there is a glut of unsold homes. Defaults and foreclosures are rising, putting further pressure on home prices and mortgage lending. Some housing industry officials worry that the new infusion of capital may refuel aggressive and risky lending to people with poor credit, known as subprime borrowers, delaying a much-needed winnowing of the business. Among those making the biggest bets is Cerberus Capital Management as it acquired control of the subprime lender Residential Capital last year, when it led an investment consortium that bought a 51 percent stake in G.M.A.C., the finance arm of General Motors. In the last several months, however, private equity firms and others have acquired, taken stakes in or provided fresh capital to companies that wrote nearly 20 percent of last year’s $600 billion in subprime loans.