4 Min Read NEW YORK, July 29 (Reuters) - Investors looking for clear guidelines on when the Federal Reserve will begin tapering its massive bond purchases were left waiting Wednesday, with all eyes next on the annual Jackson Hole conference of central bankers in August. The central bank has been buying $120 billion in fixed income assets per month - $80 billion in Treasuries and $40 billion in mortgage-backed securities - to support the economy as it recovers from the impact of the coronavirus pandemic, and markets have been fixated on when the Fed will start tapering. Powell said in June that there had been initial discussions about when to pull back.