Treasuries extended losses as Federal Reserve Chair Janet Yellen signaled that a change in the central bank’s guidance on interest rates won’t lock it into a timetable for tightening. U.S. government securities are already on course for the biggest monthly loss since 2009, according to Bank of America Merrill Lynch indexes, as rising wages and payrolls fuel speculation the Fed may increase borrowing costs as soon as June. “She has to emphasize the economy is doing well,” David Keeble, head of fixed-income strategy at Credit Agricole SA in New York, said before Yellen spoke. The benchmark 10-year yield climbed four ... (full story)