Lenders must consider borrowers' ability to pay the full cost of the loan WASHINGTON (MarketWatch) -- Cracking down on exotic mortgages that have exploded in popularity in recent years, U.S. regulators told banks Friday that they've got to make sure that borrowers can actually pay back the full amount of the mortgage. Exotic products, such as interest-only or payment option adjustable rate mortgages, allow borrowers to trade lower initial payments for higher payments later. But such products have raised red flags at the Federal Reserve and other banking regulators as more institutions offer them and they become available to a...