Vermont house sellers may be gloomy these days, but house buyers with ready cash may be smiling about some recent news. Now a new study by the U.S. Federal Reserve says Vermonts house prices may fall further as credit availability tightens. "(Vermont) house prices may still fall in the future," wrote the researchers. "Any change in the ability to purchase a home, such as from innovations in the lending environment, can have a large impact on the level and volatility of housing prices." The study went on to forecast that the boom-bust cycle of lending could crimp the ability of area households with a weaker credit profile to borrow. "Private mortgage originators have announced substantial changes to their subprime variable-rate mortgage programs, which are likely to result in the sharply curtailed availability of this type of credit," said the economists. Home prices in the 20 biggest U.S. cities fell 2.8 percent from a year earlier in the second quarter, according to the Standard & Poor's/Case-Shiller Home Price Index.