Could rising interest rates and a shake-up in the repo market cause some real estate investment trusts that specialize in the MBS market to dump securities en masse? A new report from Fitch Ratings notes that repurchase agreements represent 90 percent of agency mortgage REIT liabilities. “In a deleveraging scenario, MBS investors reliant on repo borrowing may need to liquidate some of their holdings,” writes Fitch analyst Robert Grossman and his team. If that happens it might create what Fitch calls a “knock-on” effect for MBS valuations and the mortgage market in general. The cash provided via repo lines is...