For bond investors worried about what might happen when the Federal Reserve starts whittling down its $2.46 trillion of Treasuries, there’s good news. The central bank plans to reduce its debt holdings sometime after it starts raising interest rates, and the concern is that the Fed’s attempt to reverse its unprecedented easy-money policies will trigger a jump in borrowing costs. “It would not have an impact, and that’s the news here,” said Lou Crandall, chief economist at Wrightson ICAP LLC, a research firm that specializes in analyzing Fed policy and Treasury financing.