Speculators, in the form of “short-sellers,” are zeroing in on the mortgage industry, including some of the fastest-growing servicers of the past two years: Nationstar Mortgage, Ocwen Financial, and Walter Investment Management Corp. But one mortgage stock being shorted more than any of these is PHH Corp., the parent company of PHH Mortgage, the nation’s seventh largest originator. According to figures compiled by Standard & Poor’s, as of early February, speculators had sold short 17.2 million shares of PHH common. As a ratio of shares outstanding in PHH, this comes...[Includes one data chart]