"In 2003, of all new mortgages, 10.2 percent were interest-only, meaning the homeowner paid only the interest for the initial period of the loan. According to Loan Performance, a research firm, 26.7 percent of all loans were interest-only last year and another 15.3 percent were payment-option adjustable rate mortgages, which allow homeowners to choose how much they paid each month."The problem is more concentrated in some regions: "In most California cities, as well as in Denver, Washington, Phoenix and Seattle, interest-only loans represented 40 percent or more of all mortgages issued in 2005."