One common assumption about the subprime mortgage crisis is that it revolves around borrowers with sketchy credit who couldn’t have bought a home without paying punitively high interest rates. But it turns out that plenty of people with seemingly good credit are also caught in the subprime trap.

An analysis for The Wall Street Journal of more than $2.5 trillion in subprime loans made since 2000 shows that as the number of subprime loans mushroomed, an increasing proportion of them went to people with credit scores high enough to often qualify for conventional loans with far better terms.

In 2005, the peak year of the subprime boom, the study says that borrowers with such credit scores got more than half — 55% — of all subprime mortgages that were ultimately packaged into securities for sale to investors, as most subprime loans are. The study by First American LoanPerformance, a San Francisco research firm, says the proportion rose even higher by the end of 2006, to 61%. The figure was just 41% in 2000, according to the study. Even a significant number of borrowers with top-notch credit signed up for expensive subprime loans, the firm’s analysis found.

The numbers could have dramatic implications for how banks and U.S. regulators address the meltdown in subprime loans. Major banks, mortgage companies and investment firms have been rocked by billions of dollars in losses as shaky subprime loans — which typically carry much higher, or rising, rates and other potentially onerous costs — have increasingly gone into default. Many analysts expect hundreds of thousands more loans could go bad over the next several years. The Bush administration and major financial institutions are working on a plan to freeze interest rates of certain subprime loans in hopes of avoiding an even bigger meltdown.

Subprime Debacle Traps Even Very Credit-Worthy