The US housing market crash triggered the 2008 financial crisis and fueled a wave of mortgage defaults and foreclosures over the past two years. Now, growing numbers of well heeled Americans, their portfolios hammered by depressed markets, have stopped repaying loans or even walked away from mortgages. “The affluent are not immune to the recession. It just took a while to manifest itself,” said Jay Welker, chief executive of Wells Fargo Private Bank. “In this economy, the high net worth segment has had to de-leverage itself as well.”