Banks and other investors are taking on more risks in the mortgage market, according to analysts at Standard & Poor’s, but they should be able to withstand any bursting of the housing bubble. In a conference call this week, S&P Chief Economist David Wyss said the average U.S. home is selling for 3.1 times the average household income. That compares to a historical average price of 2.6 times household income over the past 45…