Dramatic home price gains in some of America’s largest cities point to a potentially new housing bubble in those areas, according to Robert Shiller, who helped create a closely watched gauge of U.S. housing prices. Shiller said big price gains in Las Vegas, Los Angeles, San Francisco, Miami and Phoenix, fueled in part by a large influx of outside investor money, are a possible sign of trouble ahead. “There is a risk of bubbles in these cities,” Shiller, a co-founder of the S&P/Case-Shiller Home Price Index, told Reuters on Wednesday. “House prices increases have been dramatic. It looks like the...